Merge #22: Check whether initerrormessage.qml is loaded correctly

15b7c5a qml: Check whether initerrormessage.qml is loaded correctly (Hennadii Stepanov)

Pull request description:

  If `QQmlApplicationEngine::load()` fails calling `qGuiApp->exec()` must be avoided.

ACKs for top commit:
  jarolrod:
    ACK 15b7c5a

Tree-SHA512: 5e9a319b6de270cacf654e8de2e65850e749960b152a8a2bf134d0c2e66af5997916ea51ad9a817c2a4215de0f95da20a68eb2647de41b256a52477fa227a447

src/qml/bitcoin.cpp

@@ -51,6 +51,9 @@ bool InitErrorMessageBox(
     QQmlApplicationEngine engine;
     engine.rootContext()->setContextProperty("message", QString::fromStdString(message.translated));
     engine.load(QUrl(QStringLiteral("qrc:///qml/pages/initerrormessage.qml")));
+    if (engine.rootObjects().isEmpty()) {
+        return EXIT_FAILURE;
+    }
     qGuiApp->exec();
     return false;
 }