Enhance thread safety of loaders and importers

core/io/resource_loader.h

@@ -218,18 +218,20 @@ public:
 	static void set_timestamp_on_load(bool p_timestamp) { timestamp_on_load = p_timestamp; }
 	static bool get_timestamp_on_load() { return timestamp_on_load; }
 
+	// Loaders can safely use this regardless which thread they are running on.
 	static void notify_load_error(const String &p_err) {
 		if (err_notify) {
-			err_notify(p_err);
+			callable_mp_static(err_notify).bind(p_err).call_deferred();
 		}
 	}
 	static void set_error_notify_func(ResourceLoadErrorNotify p_err_notify) {
 		err_notify = p_err_notify;
 	}
 
+	// Loaders can safely use this regardless which thread they are running on.
 	static void notify_dependency_error(const String &p_path, const String &p_dependency, const String &p_type) {
 		if (dep_err_notify) {
-			dep_err_notify(p_path, p_dependency, p_type);
+			callable_mp_static(dep_err_notify).bind(p_path, p_dependency, p_type).call_deferred();
 		}
 	}
 	static void set_dependency_error_notify_func(DependencyErrorNotify p_err_notify) {

editor/editor_node.cpp

@@ -4115,6 +4115,7 @@ void EditorNode::notify_all_debug_sessions_exited() {
 }
 
 void EditorNode::add_io_error(const String &p_error) {
+	DEV_ASSERT(Thread::get_caller_id() == Thread::get_main_id());
 	singleton->load_errors->add_image(singleton->gui_base->get_theme_icon(SNAME("Error"), SNAME("EditorIcons")));
 	singleton->load_errors->add_text(p_error + "\n");
 	singleton->load_error_dialog->attach_and_popup_centered_ratio(0.5);

editor/editor_node.h

@@ -505,6 +505,7 @@ private:
 	static Vector<EditorNodeInitCallback> _init_callbacks;
 
 	static void _dependency_error_report(const String &p_path, const String &p_dep, const String &p_type) {
+		DEV_ASSERT(Thread::get_caller_id() == Thread::get_main_id());
 		if (!singleton->dependency_errors.has(p_path)) {
 			singleton->dependency_errors[p_path] = HashSet<String>();
 		}

editor/import/editor_import_collada.cpp

@@ -1782,15 +1782,8 @@ Node *EditorSceneFormatImporterCollada::import_scene(const String &p_path, uint3
 	ERR_FAIL_COND_V_MSG(err != OK, nullptr, "Cannot load scene from file '" + p_path + "'.");
 
 	if (state.missing_textures.size()) {
-		/*
-	for(int i=0;i<state.missing_textures.size();i++) {
-		EditorNode::add_io_error("Texture Not Found: "+state.missing_textures[i]);
-	}
-	*/
-
 		if (r_missing_deps) {
 			for (int i = 0; i < state.missing_textures.size(); i++) {
-				//EditorNode::add_io_error("Texture Not Found: "+state.missing_textures[i]);
 				r_missing_deps->push_back(state.missing_textures[i]);
 			}
 		}

editor/import/resource_importer_shader_file.cpp

@@ -106,7 +106,7 @@ Error ResourceImporterShaderFile::import(const String &p_source_file, const Stri
 
 	if (err != OK) {
 		if (!ShaderFileEditor::singleton->is_visible_in_tree()) {
-			EditorNode::get_singleton()->add_io_error(vformat(TTR("Error importing GLSL shader file: '%s'. Open the file in the filesystem dock in order to see the reason."), p_source_file));
+			callable_mp_static(&EditorNode::add_io_error).bind(vformat(TTR("Error importing GLSL shader file: '%s'. Open the file in the filesystem dock in order to see the reason."), p_source_file)).call_deferred();
 		}
 	}