I installed the Linux binary on Arch using flatpak.

When the app crashes, it cannot start again. It thinks that the app is still running, and tries to connect to it:

> flatpak run org.strawberrymusicplayer.strawberry
13:24:25.639 INFO  main:165                         Strawberry is already running - activating existing window (1)
13:24:30.689 WARN  unknown                          Connection timed out 
13:24:30.690 ERROR main:168                         Could not send message to primary instance.

But the app is obviously not running:

> ps -ef | grep strawberry
user      123329  115326  0 13:31 pts/1    00:00:00 grep --color=auto strawberry
> flatpak kill org.strawberrymusicplayer.strawberry
error: org.strawberrymusicplayer.strawberry is not running

Is there a socket left open somewhere? How can I close it so that I can run the app again?