TextEditor: fix crash on setting text cursor

Setting a text cursor with a currently open edit block results in
crashes.

Fixes: QTCREATORBUG-21471
Change-Id: I267cdaf10b20959654c2923e5dcc0a07793f3094
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/texteditor/texteditor.cpp

@@ -2492,9 +2492,9 @@ void TextEditorWidget::keyPressEvent(QKeyEvent *e)
                     d->autocompleterHighlight(tc);
                 }
             }
+            cursor.endEditBlock();
             setTextCursor(ensureVisible);
             cursor.setPosition(cursorPosition);
-            cursor.endEditBlock();
         }
 
         setTextCursor(cursor);