WebServer+LibGUI: Use fallible version of StringBuilder::to_byte_buffer

...and simply ignore the errors for now. This allows us to remove the
infallible function and avoid accumulating more callers of it.

Userland/Libraries/LibGUI/Model.cpp

@@ -125,7 +125,7 @@ RefPtr<Core::MimeData> Model::mime_data(ModelSelection const& selection) const
         }
     });
 
-    mime_data->set_data(drag_data_type(), data_builder.to_byte_buffer());
+    mime_data->set_data(drag_data_type(), data_builder.try_to_byte_buffer().release_value_but_fixme_should_propagate_errors());
     mime_data->set_text(text_builder.to_deprecated_string());
     if (bitmap)
         mime_data->set_data("image/x-raw-bitmap", bitmap->serialize_to_byte_buffer().release_value_but_fixme_should_propagate_errors());

Userland/Services/WebServer/Client.cpp

@@ -81,7 +81,7 @@ void Client::start()
             builder.append("\r\n"sv);
         }
 
-        auto request = builder.to_byte_buffer();
+        auto request = builder.try_to_byte_buffer().release_value_but_fixme_should_propagate_errors();
         dbgln_if(WEBSERVER_DEBUG, "Got raw request: '{}'", DeprecatedString::copy(request));
 
         auto maybe_did_handle = handle_request(request);