WebContent+LibWeb+LibJS: Report exceptions to the JS console

Print exceptions passed to `HTML::report_exception` in the JS console

Refactored `ExceptionReporter`: in order to report exception now
you need to pass the relevant realm in it. For passed `JS::Value`
we now create `JS::Error` object to print value as the error message.

Userland/Libraries/LibJS/Console.cpp

@@ -453,6 +453,12 @@ void Console::output_debug_message([[maybe_unused]] LogLevel log_level, [[maybe_
 #endif
 }
 
+void Console::report_exception(JS::Error const& exception, bool in_promise) const
+{
+    if (m_client)
+        m_client->report_exception(exception, in_promise);
+}
+
 ThrowCompletionOr<String> Console::value_vector_to_string(MarkedVector<Value> const& values)
 {
     auto& vm = realm().vm();

Userland/Libraries/LibJS/Console.h

@@ -82,6 +82,7 @@ public:
     ThrowCompletionOr<Value> time_end();
 
     void output_debug_message(LogLevel log_level, String output) const;
+    void report_exception(JS::Error const&, bool) const;
 
 private:
     ThrowCompletionOr<String> value_vector_to_string(MarkedVector<Value> const&);
@@ -108,7 +109,8 @@ public:
     ThrowCompletionOr<MarkedVector<Value>> formatter(MarkedVector<Value> const& args);
     virtual ThrowCompletionOr<Value> printer(Console::LogLevel log_level, PrinterArguments) = 0;
 
-    virtual void add_css_style_to_current_message(StringView) {};
+    virtual void add_css_style_to_current_message(StringView) { }
+    virtual void report_exception(JS::Error const&, bool) { }
 
     virtual void clear() = 0;
     virtual void end_group() = 0;

Userland/Libraries/LibJS/MarkupGenerator.cpp

@@ -36,11 +36,10 @@ String MarkupGenerator::html_from_value(Value value)
     return output_html.to_string();
 }
 
-String MarkupGenerator::html_from_error(Object& object)
+String MarkupGenerator::html_from_error(Error const& object, bool in_promise)
 {
     StringBuilder output_html;
-    HashTable<Object*> seen_objects;
+    error_to_html(object, output_html, in_promise);
-    error_to_html(object, output_html, seen_objects);
     return output_html.to_string();
 }
 
@@ -70,8 +69,6 @@ void MarkupGenerator::value_to_html(Value value, StringBuilder& output_html, Has
             return function_to_html(object, output_html, seen_objects);
         if (is<Date>(object))
             return date_to_html(object, output_html, seen_objects);
-        if (is<Error>(object))
-            return error_to_html(object, output_html, seen_objects);
         return object_to_html(object, output_html, seen_objects);
     }
 
@@ -145,19 +142,35 @@ void MarkupGenerator::date_to_html(Object const& date, StringBuilder& html_outpu
     html_output.appendff("Date {}", to_date_string(static_cast<Date const&>(date).date_value()));
 }
 
-void MarkupGenerator::error_to_html(Object const& object, StringBuilder& html_output, HashTable<Object*>&)
+void MarkupGenerator::trace_to_html(TracebackFrame const& traceback_frame, StringBuilder& html_output)
 {
-    auto& vm = object.vm();
+    auto function_name = escape_html_entities(traceback_frame.function_name);
-    auto name = object.get_without_side_effects(vm.names.name).value_or(js_undefined());
+    auto [line, column, _] = traceback_frame.source_range.start;
-    auto message = object.get_without_side_effects(vm.names.message).value_or(js_undefined());
+    auto get_filename_from_path = [&](StringView filename) -> StringView {
-    if (name.is_accessor() || message.is_accessor()) {
+        auto last_slash_index = filename.find_last('/');
-        html_output.append(wrap_string_in_style(Value(&object).to_string_without_side_effects(), StyleType::Invalid));
+        return last_slash_index.has_value() ? filename.substring_view(*last_slash_index + 1) : filename;
-    } else {
+    };
-        auto name_string = name.to_string_without_side_effects();
+    auto filename = escape_html_entities(get_filename_from_path(traceback_frame.source_range.filename));
-        auto message_string = message.to_string_without_side_effects();
+    auto trace = String::formatted("at {} ({}:{}:{})", function_name, filename, line, column);
-        html_output.append(wrap_string_in_style(String::formatted("[{}]", name_string), StyleType::Invalid));
+
-        if (!message_string.is_empty())
+    html_output.appendff("&nbsp;&nbsp;{}<br>", trace);
-            html_output.appendff(": {}", escape_html_entities(message_string));
+}
+
+void MarkupGenerator::error_to_html(Error const& error, StringBuilder& html_output, bool in_promise)
+{
+    auto& vm = error.vm();
+    auto name = error.get_without_side_effects(vm.names.name).value_or(js_undefined());
+    auto message = error.get_without_side_effects(vm.names.message).value_or(js_undefined());
+    auto name_string = name.to_string_without_side_effects();
+    auto message_string = message.to_string_without_side_effects();
+    auto uncaught_message = String::formatted("Uncaught {}[{}]: ", in_promise ? "(in promise) " : "", name_string);
+
+    html_output.append(wrap_string_in_style(uncaught_message, StyleType::Invalid));
+    html_output.appendff("{}<br>", message_string.is_empty() ? "\"\"" : escape_html_entities(message_string));
+
+    for (size_t i = 0; i < error.traceback().size() - min(error.traceback().size(), 3); i++) {
+        auto& traceback_frame = error.traceback().at(i);
+        trace_to_html(traceback_frame, html_output);
     }
 }
 

Userland/Libraries/LibJS/MarkupGenerator.h

@@ -9,6 +9,7 @@
 #include <AK/HashTable.h>
 #include <AK/String.h>
 #include <LibJS/Forward.h>
+#include <LibJS/Runtime/Error.h>
 
 namespace JS {
 
@@ -16,7 +17,7 @@ class MarkupGenerator {
 public:
     static String html_from_source(StringView);
     static String html_from_value(Value);
-    static String html_from_error(Object&);
+    static String html_from_error(Error const&, bool);
 
 private:
     enum class StyleType {
@@ -37,7 +38,8 @@ private:
     static void object_to_html(Object const&, StringBuilder& output_html, HashTable<Object*>&);
     static void function_to_html(Object const&, StringBuilder& output_html, HashTable<Object*>&);
     static void date_to_html(Object const&, StringBuilder& output_html, HashTable<Object*>&);
-    static void error_to_html(Object const&, StringBuilder& output_html, HashTable<Object*>&);
+    static void error_to_html(Error const&, StringBuilder& output_html, bool in_promise);
+    static void trace_to_html(TracebackFrame const&, StringBuilder& output_html);
 
     static String style_from_style_type(StyleType);
     static StyleType style_type_for_token(Token);

Userland/Libraries/LibWeb/Bindings/MainThreadVM.cpp

@@ -202,7 +202,7 @@ JS::VM& main_thread_vm()
 
                 // 6. If result is an abrupt completion, then report the exception given by result.[[Value]].
                 if (result.is_error())
-                    HTML::report_exception(result);
+                    HTML::report_exception(result, finalization_registry.realm());
             });
         };
 
@@ -275,7 +275,7 @@ JS::VM& main_thread_vm()
 
                 // 5. If result is an abrupt completion, then report the exception given by result.[[Value]].
                 if (result.is_error())
-                    HTML::report_exception(result);
+                    HTML::report_exception(result, job_settings->realm());
             });
         };
 
@@ -437,7 +437,7 @@ void queue_mutation_observer_microtask(DOM::Document& document)
 
                 auto result = WebIDL::invoke_callback(callback, mutation_observer.ptr(), wrapped_records, mutation_observer.ptr());
                 if (result.is_abrupt())
-                    HTML::report_exception(result);
+                    HTML::report_exception(result, realm);
             }
         }
 

Userland/Libraries/LibWeb/DOM/Document.cpp

@@ -1139,7 +1139,7 @@ JS::Value Document::run_javascript(StringView source, StringView filename)
 
     if (result.is_error()) {
         // FIXME: I'm sure the spec could tell us something about error propagation here!
-        HTML::report_exception(result);
+        HTML::report_exception(result, realm());
 
         return {};
     }

Userland/Libraries/LibWeb/DOM/EventDispatcher.cpp

@@ -114,7 +114,7 @@ bool EventDispatcher::inner_invoke(Event& event, Vector<JS::Handle<DOM::DOMEvent
         // If this throws an exception, then:
         if (result.is_error()) {
             // 1. Report the exception.
-            HTML::report_exception(result);
+            HTML::report_exception(result, realm);
 
             // FIXME: 2. Set legacyOutputDidListenersThrowFlag if given. (Only used by IndexedDB currently)
         }

Userland/Libraries/LibWeb/HTML/Scripting/ClassicScript.cpp

@@ -133,7 +133,7 @@ JS::Completion ClassicScript::run(RethrowErrors rethrow_errors)
         dbgln("no rethrow, stat: {}", evaluation_status.value().value().to_string_without_side_effects());
 
         // 1. Report the exception given by evaluationStatus.[[Value]] for script.
-        report_exception(evaluation_status);
+        report_exception(evaluation_status, settings_object().realm());
 
         // 2. Clean up after running script with settings.
         settings.clean_up_after_running_script();

Userland/Libraries/LibWeb/HTML/Scripting/Environments.cpp

@@ -239,7 +239,7 @@ void EnvironmentSettingsObject::notify_about_rejected_promises(Badge<EventLoop>)
             // This algorithm results in promise rejections being marked as handled or not handled. These concepts parallel handled and not handled script errors.
             // If a rejection is still not handled after this, then the rejection may be reported to a developer console.
             if (not_handled)
-                HTML::print_error_from_value(promise.result(), ErrorInPromise::Yes);
+                HTML::report_exception_to_console(promise.result(), realm(), ErrorInPromise::Yes);
         }
     });
 }

Userland/Libraries/LibWeb/HTML/Scripting/ExceptionReporter.cpp

@@ -5,15 +5,19 @@
  */
 
 #include <AK/TypeCasts.h>
+#include <LibJS/Console.h>
+#include <LibJS/Runtime/ConsoleObject.h>
 #include <LibJS/Runtime/VM.h>
 #include <LibJS/Runtime/Value.h>
+#include <LibWeb/Bindings/MainThreadVM.h>
 #include <LibWeb/HTML/Scripting/ExceptionReporter.h>
 
 namespace Web::HTML {
 
-void print_error_from_value(JS::Value value, ErrorInPromise error_in_promise)
+void report_exception_to_console(JS::Value value, JS::Realm& realm, ErrorInPromise error_in_promise)
 {
-    // FIXME: We should probably also report these exceptions to the JS console.
+    auto& console = realm.intrinsics().console_object()->console();
+
     if (value.is_object()) {
         auto& object = value.as_object();
         auto& vm = object.vm();
@@ -27,24 +31,28 @@ void print_error_from_value(JS::Value value, ErrorInPromise error_in_promise)
         }
         if (is<JS::Error>(object)) {
             auto const& error_value = static_cast<JS::Error const&>(object);
-            for (auto const& traceback_frame : error_value.traceback()) {
+            for (auto& traceback_frame : error_value.traceback()) {
-                auto const& function_name = traceback_frame.function_name;
+                auto& function_name = traceback_frame.function_name;
-                auto const& source_range = traceback_frame.source_range;
+                auto& source_range = traceback_frame.source_range;
                 dbgln("  {} at {}:{}:{}", function_name, source_range.filename, source_range.start.line, source_range.start.column);
             }
+            console.report_exception(error_value, error_in_promise == ErrorInPromise::Yes);
+
+            return;
         }
     } else {
-        dbgln("\033[31;1mUnhandled JavaScript exception:\033[0m {}", value);
+        dbgln("\033[31;1mUnhandled JavaScript exception{}:\033[0m {}", error_in_promise == ErrorInPromise::Yes ? " (in promise)" : "", value);
     }
+
+    console.report_exception(*JS::Error::create(realm, value.to_string_without_side_effects()), error_in_promise == ErrorInPromise::Yes);
 }
 
 // https://html.spec.whatwg.org/#report-the-exception
-void report_exception(JS::Completion const& throw_completion)
+void report_exception(JS::Completion const& throw_completion, JS::Realm& realm)
 {
-    // FIXME: This is just old code, and does not strictly follow the spec of report an exception.
     VERIFY(throw_completion.type() == JS::Completion::Type::Throw);
     VERIFY(throw_completion.value().has_value());
-    print_error_from_value(*throw_completion.value(), ErrorInPromise::No);
+    report_exception_to_console(*throw_completion.value(), realm, ErrorInPromise::No);
 }
 
 }

Userland/Libraries/LibWeb/HTML/Scripting/ExceptionReporter.h

@@ -15,14 +15,14 @@ enum class ErrorInPromise {
     Yes,
 };
 
-void print_error_from_value(JS::Value, ErrorInPromise);
+void report_exception_to_console(JS::Value, JS::Realm&, ErrorInPromise);
-void report_exception(JS::Completion const&);
+void report_exception(JS::Completion const&, JS::Realm&);
 
 template<typename T>
-inline void report_exception(JS::ThrowCompletionOr<T> const& result)
+inline void report_exception(JS::ThrowCompletionOr<T> const& result, JS::Realm& realm)
 {
     VERIFY(result.is_throw_completion());
-    report_exception(result.throw_completion());
+    report_exception(result.throw_completion(), realm);
 }
 
 }

Userland/Libraries/LibWeb/HTML/Window.cpp

@@ -201,7 +201,7 @@ i32 Window::run_timer_initialization_steps(TimerHandler handler, i32 timeout, JS
             // 2. If handler is a Function, then invoke handler given arguments with the callback this value set to thisArg. If this throws an exception, catch it, and report the exception.
             [&](JS::Handle<WebIDL::CallbackType> callback) {
                 if (auto result = WebIDL::invoke_callback(*callback, window.ptr(), arguments); result.is_error())
-                    HTML::report_exception(result);
+                    HTML::report_exception(result, weak_window->realm());
             },
             // 3. Otherwise:
             [&](String const& source) {
@@ -271,7 +271,7 @@ i32 Window::request_animation_frame_impl(WebIDL::CallbackType& js_callback)
 
         // and if an exception is thrown, report the exception.
         if (result.is_error())
-            HTML::report_exception(result);
+            HTML::report_exception(result, realm());
     });
 }
 
@@ -495,11 +495,15 @@ void Window::fire_a_page_transition_event(FlyString const& event_name, bool pers
 void Window::queue_microtask_impl(WebIDL::CallbackType& callback)
 {
     // The queueMicrotask(callback) method must queue a microtask to invoke callback,
-    HTML::queue_a_microtask(&associated_document(), [&callback]() mutable {
+    HTML::queue_a_microtask(&associated_document(), [weak_window = make_weak_ptr<Window>(), &callback]() mutable {
+        JS::GCPtr<Window> window = weak_window.ptr();
+        if (!window)
+            return;
+
         auto result = WebIDL::invoke_callback(callback, {});
         // and if callback throws an exception, report the exception.
         if (result.is_error())
-            HTML::report_exception(result);
+            HTML::report_exception(result, window->realm());
     });
 }
 
@@ -655,7 +659,7 @@ void Window::invoke_idle_callbacks()
         // 3. Call callback with deadlineArg as its argument. If an uncaught runtime script error occurs, then report the exception.
         auto result = callback->invoke(deadline_arg);
         if (result.is_error())
-            HTML::report_exception(result);
+            HTML::report_exception(result, realm());
         // 4. If window's list of runnable idle callbacks is not empty, queue a task which performs the steps
         //    in the invoke idle callbacks algorithm with getDeadline and window as a parameters and return from this algorithm
         HTML::queue_global_task(HTML::Task::Source::IdleTask, *this, [this]() mutable {

Userland/Services/WebContent/WebContentConsoleClient.cpp

@@ -49,23 +49,15 @@ void WebContentConsoleClient::handle_input(String const& js_source)
 
     auto result = script->run();
 
-    StringBuilder output_html;
-
-    if (result.is_abrupt()) {
-        output_html.append("Uncaught exception: "sv);
-        auto error = *result.release_error().value();
-        if (error.is_object())
-            output_html.append(JS::MarkupGenerator::html_from_error(error.as_object()));
-        else
-            output_html.append(JS::MarkupGenerator::html_from_value(error));
-        print_html(output_html.string_view());
-        return;
-    }
-
     if (result.value().has_value())
         print_html(JS::MarkupGenerator::html_from_value(*result.value()));
 }
 
+void WebContentConsoleClient::report_exception(JS::Error const& exception, bool in_promise)
+{
+    print_html(JS::MarkupGenerator::html_from_error(exception, in_promise));
+}
+
 void WebContentConsoleClient::print_html(String const& line)
 {
     m_message_log.append({ .type = ConsoleOutput::Type::HTML, .data = line });

Userland/Services/WebContent/WebContentConsoleClient.h

@@ -22,6 +22,7 @@ public:
 
     void handle_input(String const& js_source);
     void send_messages(i32 start_index);
+    void report_exception(JS::Error const&, bool) override;
 
 private:
     virtual void clear() override;