Don't access qApp directly from Platform's ctor

QApplication might not be created yet, so delay it
With a timer for now. Don't guarantee this will stay.
Explicit init by the user might be an alternative.

src/qtwidgets/Platform_qtwidgets.cpp

@@ -16,6 +16,7 @@
 #include "qtwidgets/views/ViewWrapper_qtwidgets.h"
 
 #include <QApplication>
+#include <QTimer>
 
 #include <memory.h>
 
@@ -32,9 +33,9 @@ Platform_qtwidgets::Platform_qtwidgets()
     }
 #endif
 
-    qApp->connect(qApp, &QGuiApplication::focusObjectChanged, qApp, [this](QObject *obj) {
-        ViewWrapper *wrapper = new Views::ViewWrapper_qtwidgets(obj);
-        focusedViewChanged.emit(std::shared_ptr<ViewWrapper>(wrapper));
+    // Delay call to init(), so we have a QApplication
+    QTimer::singleShot(0, [this] {
+        init();
     });
 }
 
@@ -42,6 +43,14 @@ Platform_qtwidgets::~Platform_qtwidgets()
 {
 }
 
+void Platform_qtwidgets::init()
+{
+    qApp->connect(qApp, &QGuiApplication::focusObjectChanged, qApp, [this](QObject *obj) {
+        ViewWrapper *wrapper = obj ? new Views::ViewWrapper_qtwidgets(obj) : nullptr;
+        focusedViewChanged.emit(std::shared_ptr<ViewWrapper>(wrapper));
+    });
+}
+
 const char *Platform_qtwidgets::name() const
 {
     return "qtwidgets";