Double click on internal link breaks the link picker

Double clicking an internal link in a document will open the linkpicker, but then it stops working. Closing the link picker works, but it will not function correctly anymore until you log out and in again. See the attached stacktrace.

Here is the solution sketched by Frank:
In this particular case, we can probably easily implement a quite
generic method to prevent multiple dialogs from being opened at the
same time. (an additional isShowingDialog method on the
IDialogService, coupled to a check in the DialogAction#execute should
do the job quite nicely)