Don't write global script class information if there is none

(cherry picked from commit 3163611f0c855feaf3bddad3afe9afd6fd3cc2c6)

core/script_language.cpp

@@ -276,7 +276,11 @@ void ScriptServer::save_global_classes() {
 		gcarr.push_back(d);
 	}
 
-	ProjectSettings::get_singleton()->set("_global_script_classes", gcarr);
+	if (gcarr.empty()) {
+		ProjectSettings::get_singleton()->clear("_global_script_classes");
+	} else {
+		ProjectSettings::get_singleton()->set("_global_script_classes", gcarr);
+	}
 	ProjectSettings::get_singleton()->save();
 }
 

editor/editor_data.cpp

@@ -965,7 +965,11 @@ void EditorData::script_class_save_icon_paths() {
 			d[E->get()] = _script_class_icon_paths[E->get()];
 	}
 
-	ProjectSettings::get_singleton()->set("_global_script_class_icons", d);
+	if (d.empty()) {
+		ProjectSettings::get_singleton()->clear("_global_script_class_icons");
+	} else {
+		ProjectSettings::get_singleton()->set("_global_script_class_icons", d);
+	}
 	ProjectSettings::get_singleton()->save();
 }