Require ScriptInstance to be valid in the editor debugger

This fixes an issue with visual scripts spamming error messages
in the editor when running the project with the remote scene tree
visible.

editor/debugger/editor_debugger_inspector.cpp

@@ -126,25 +126,25 @@ void EditorDebuggerInspector::_object_selected(ObjectID p_object) {
 }
 
 ObjectID EditorDebuggerInspector::add_object(const Array &p_arr) {
-	EditorDebuggerRemoteObject *debugObj = nullptr;
+	EditorDebuggerRemoteObject *debug_obj = nullptr;
 
 	SceneDebuggerObject obj;
 	obj.deserialize(p_arr);
 	ERR_FAIL_COND_V(obj.id.is_null(), ObjectID());
 
 	if (remote_objects.has(obj.id)) {
-		debugObj = remote_objects[obj.id];
+		debug_obj = remote_objects[obj.id];
 	} else {
-		debugObj = memnew(EditorDebuggerRemoteObject);
-		debugObj->remote_object_id = obj.id;
-		debugObj->type_name = obj.class_name;
-		remote_objects[obj.id] = debugObj;
-		debugObj->connect("value_edited", callable_mp(this, &EditorDebuggerInspector::_object_edited));
+		debug_obj = memnew(EditorDebuggerRemoteObject);
+		debug_obj->remote_object_id = obj.id;
+		debug_obj->type_name = obj.class_name;
+		remote_objects[obj.id] = debug_obj;
+		debug_obj->connect("value_edited", callable_mp(this, &EditorDebuggerInspector::_object_edited));
 	}
 
-	int old_prop_size = debugObj->prop_list.size();
+	int old_prop_size = debug_obj->prop_list.size();
 
-	debugObj->prop_list.clear();
+	debug_obj->prop_list.clear();
 	int new_props_added = 0;
 	HashSet<String> changed;
 	for (int i = 0; i < obj.properties.size(); i++) {
@@ -165,12 +165,14 @@ ObjectID EditorDebuggerInspector::add_object(const Array &p_arr) {
 				var = ResourceLoader::load(path);
 
 				if (pinfo.hint_string == "Script") {
-					if (debugObj->get_script() != var) {
-						debugObj->set_script(Ref<RefCounted>());
+					if (debug_obj->get_script() != var) {
+						debug_obj->set_script(Ref<RefCounted>());
 						Ref<Script> script(var);
 						if (!script.is_null()) {
-							ScriptInstance *script_instance = script->placeholder_instance_create(debugObj);
-							debugObj->set_script_and_instance(var, script_instance);
+							ScriptInstance *script_instance = script->placeholder_instance_create(debug_obj);
+							if (script_instance) {
+								debug_obj->set_script_and_instance(var, script_instance);
+							}
 						}
 					}
 				}
@@ -178,27 +180,27 @@ ObjectID EditorDebuggerInspector::add_object(const Array &p_arr) {
 		}
 
 		//always add the property, since props may have been added or removed
-		debugObj->prop_list.push_back(pinfo);
+		debug_obj->prop_list.push_back(pinfo);
 
-		if (!debugObj->prop_values.has(pinfo.name)) {
+		if (!debug_obj->prop_values.has(pinfo.name)) {
 			new_props_added++;
-			debugObj->prop_values[pinfo.name] = var;
+			debug_obj->prop_values[pinfo.name] = var;
 		} else {
-			if (bool(Variant::evaluate(Variant::OP_NOT_EQUAL, debugObj->prop_values[pinfo.name], var))) {
-				debugObj->prop_values[pinfo.name] = var;
+			if (bool(Variant::evaluate(Variant::OP_NOT_EQUAL, debug_obj->prop_values[pinfo.name], var))) {
+				debug_obj->prop_values[pinfo.name] = var;
 				changed.insert(pinfo.name);
 			}
 		}
 	}
 
-	if (old_prop_size == debugObj->prop_list.size() && new_props_added == 0) {
+	if (old_prop_size == debug_obj->prop_list.size() && new_props_added == 0) {
 		//only some may have changed, if so, then update those, if exist
 		for (const String &E : changed) {
-			emit_signal(SNAME("object_property_updated"), debugObj->remote_object_id, E);
+			emit_signal(SNAME("object_property_updated"), debug_obj->remote_object_id, E);
 		}
 	} else {
 		//full update, because props were added or removed
-		debugObj->update();
+		debug_obj->update();
 	}
 	return obj.id;
 }