Fix tests by checking if InputMethod::self() is null.

Only integration test has InputMethod instance.

src/input.cpp

@@ -1494,7 +1494,12 @@ class InputKeyboardFilter : public InputEventFilter
 public:
     bool keyEvent(QKeyEvent *event) override
     {
-        if (auto keyboardGrab = InputMethod::self()->keyboardGrab()) {
+        auto *inputmethod = InputMethod::self();
+        if (!inputmethod) {
+            return false;
+        }
+
+        if (auto keyboardGrab = inputmethod->keyboardGrab()) {
             if (event->isAutoRepeat()) {
                 return true;
             }

src/keyboard_input.cpp

@@ -248,7 +248,9 @@ void KeyboardInputRedirection::processKey(uint32_t key, InputRedirection::Keyboa
     m_input->processFilters(std::bind(&InputEventFilter::keyEvent, std::placeholders::_1, &event));
 
     m_xkb->forwardModifiers();
-    InputMethod::self()->forwardModifiers(InputMethod::NoForce);
+    if (auto *inputmethod = InputMethod::self()) {
+        inputmethod->forwardModifiers(InputMethod::NoForce);
+    }
 
     if (event.modifiersRelevantForGlobalShortcuts() == Qt::KeyboardModifier::NoModifier && type != QEvent::KeyRelease) {
         m_keyboardLayout->checkLayoutChange(previousLayout);