LibWeb: Properly implement IDBRequest::error()

Author: https://github.com/stelar7
Commit: https://github.com/LadybirdBrowser/ladybird/commit/204d776cdb3
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/2236
Reviewed-by: https://github.com/gmta ✅

Libraries/LibWeb/IndexedDB/IDBRequest.cpp

@@ -65,4 +65,15 @@ WebIDL::CallbackType* IDBRequest::onerror()
     return m_done ? Bindings::IDBRequestReadyState::Done : Bindings::IDBRequestReadyState::Pending;
 }
 
+// https://w3c.github.io/IndexedDB/#dom-idbrequest-error
+[[nodiscard]] WebIDL::ExceptionOr<GC::Ptr<WebIDL::DOMException>> IDBRequest::error() const
+{
+    // 1. If this's done flag is false, then throw an "InvalidStateError" DOMException.
+    if (!m_done)
+        return WebIDL::InvalidStateError::create(realm(), "The request is not done"_string);
+
+    // 2. Otherwise, return this's error, or null if no error occurred.
+    return m_error;
+}
+
 }

Libraries/LibWeb/IndexedDB/IDBRequest.h

@@ -23,12 +23,12 @@ public:
     virtual ~IDBRequest() override;
 
     [[nodiscard]] JS::Value result() const { return m_result; }
-    [[nodiscard]] GC::Ptr<WebIDL::DOMException> error() const { return m_error; }
     [[nodiscard]] bool done() const { return m_done; }
     [[nodiscard]] bool processed() const { return m_processed; }
     [[nodiscard]] IDBRequestSource source() const { return m_source; }
 
     [[nodiscard]] Bindings::IDBRequestReadyState ready_state() const;
+    [[nodiscard]] WebIDL::ExceptionOr<GC::Ptr<WebIDL::DOMException>> error() const;
 
     void set_done(bool done) { m_done = done; }
     void set_result(JS::Value result) { m_result = result; }