Where can I find logs for this app

[ChibyX]

I have a problem with app, so I would like to find out what causes it

[oscfdezdz]

Running it from the terminal should give you some details about crashes.

Flatpak: flatpak run com.mattjakeman.ExtensionManager

Traditional package: extension-manager

For more advanced logging you can use gdb:

For Flatpak, check https://docs.flatpak.org/en/latest/debugging.html

For traditional package formats, install gdb and run: gdb extension-manager, type run and when the crash or bug occurs, bt.