Don't crash if a plugin has invalid QML

src/Application.cc

@@ -387,6 +387,9 @@ bool Application::LoadPlugin(const std::string &_filename,
   else
     plugin->Load(_pluginElem);
 
+  if (nullptr == plugin->CardItem())
+    return false;
+
   // Store plugin in queue to be added to the window
   this->dataPtr->pluginsToAdd.push(plugin);
 

src/Application_TEST.cc

@@ -136,6 +136,14 @@ TEST(ApplicationTest, IGN_UTILS_TEST_DISABLED_ON_WIN32(LoadPlugin))
 
     EXPECT_FALSE(app.LoadPlugin("TestNotRegisteredPlugin"));
   }
+
+  // Plugin with invalid QML
+  {
+    Application app(g_argc, g_argv);
+    app.AddPluginPath(std::string(PROJECT_BINARY_PATH) + "/lib");
+
+    EXPECT_FALSE(app.LoadPlugin("TestInvalidQmlPlugin"));
+  }
 }
 
 //////////////////////////////////////////////////

test/plugins/CMakeLists.txt

@@ -11,6 +11,7 @@ link_directories(
 
 set (plugins
   TestBadInheritancePlugin
+  TestInvalidQmlPlugin
   TestNotRegisteredPlugin
   TestPlugin
 )

test/plugins/TestInvalidQmlPlugin.cc

@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2021 Open Source Robotics Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+*/
+
+#include <ignition/plugin/Register.hh>
+
+#include "TestInvalidQmlPlugin.hh"
+
+using namespace ignition;
+using namespace gui;
+
+/////////////////////////////////////////////////
+TestInvalidQmlPlugin::TestInvalidQmlPlugin()
+  : Plugin()
+{
+}
+
+/////////////////////////////////////////////////
+TestInvalidQmlPlugin::~TestInvalidQmlPlugin()
+{
+}
+
+// Register this plugin
+IGNITION_ADD_PLUGIN(ignition::gui::TestInvalidQmlPlugin,
+                    ignition::gui::Plugin)

test/plugins/TestInvalidQmlPlugin.hh

@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2021 Open Source Robotics Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+*/
+
+#ifndef IGNITION_GUI_TEST_MALFORMEDPLUGIN_HH_
+#define IGNITION_GUI_TEST_MALFORMEDPLUGIN_HH_
+
+#include <ignition/gui/Plugin.hh>
+
+namespace ignition
+{
+  namespace gui
+  {
+    class TestInvalidQmlPlugin : public Plugin
+    {
+      Q_OBJECT
+
+      /// \brief Constructor
+      public: TestInvalidQmlPlugin();
+
+      /// \brief Destructor
+      public: virtual ~TestInvalidQmlPlugin();
+    };
+  }
+}
+
+#endif

test/plugins/TestInvalidQmlPlugin.qml

@@ -0,0 +1,21 @@
+/*
+ * Copyright (C) 2021 Open Source Robotics Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+*/
+import QtQuick 2.9
+
+Rectangle {
+  banana: fail
+}

test/plugins/TestInvalidQmlPlugin.qrc

@@ -0,0 +1,5 @@
+<!DOCTYPE RCC><RCC version="1.0">
+<qresource prefix="TestInvalidQmlPlugin/">
+  <file>TestInvalidQmlPlugin.qml</file>
+</qresource>
+</RCC>