FakeVim: Check handler pointer before using it

Shouldn't happen in that case. But better safe than sorry.

Change-Id: I8461fec32c23e7efe6c949724cf522b58b703acc
Reviewed-by: Lukas Holecek <hluk@email.cz>
Reviewed-by: Eike Ziller <eike.ziller@digia.com>

src/plugins/fakevim/fakevimplugin.cpp

@@ -2123,6 +2123,7 @@ void FakeVimPluginPrivate::showExtraInformation(const QString &text)
     IEditor *iedit = EditorManager::openEditorWithContents(Id(), &title, text.toUtf8());
     EditorManager::activateEditor(iedit);
     FakeVimHandler *handler = m_editorToHandler.value(iedit, 0);
+    QTC_ASSERT(handler, return);
     handler->handleCommand(_("0"));
 }