Unable to exit dialog box "Missing File in Clip"

[Klaatu Verata Necto]

- OpenShot-v2.3.1-x86_64.exe
- Windows 10 x64

Steps to reproduce:
- Open new project
- Import video clip and add it to the timeline
- Save project
- Exit OpenShot
- Remove imported video clip from its physical location
- Open OpenShot

At this point a dialog box pops up "Missing File in Clip".
Clicking "X" or "OK" keeps asking for file location and it is impossible to close the dialog.

Later I found you have to repeat it several times to actually close it. In my humble opinion there should be a button "Cancel" which gives me an option to further use the software if I don't care about the missing file.