I don't know if this bug has been identified by the developers, but this bug has been persistent through all the versions of Recalbox.
The following description is when you are working within the emulationstation GUI:
So essentially what happens is if you are deleting the last ROM within a system and there are no more ROMs within that system, recalbox crashes. This is definitely more prevalent with screenshots, when you are deleting images. If you delete the last image within imageviewer, recalbox crashes.
I had to disconnect the power since I turned off networking, so I am not sure if recalbox itself crashes, or if its just emulationstation. I can test further if anyone needs me to.