Deadlock in load_system with wrong path

[parmigggiana]

Basilico was hanging when the pinolo sent the load system command with a wrong path, which was caused by the image folder path in pinolo not having a trailing /. That wasn't a problem in listing and selecting the image, but then the full path was sent by concatenating strings. This was fixed in 0055028, but the same problem might still be around in other parts of the codebase. It might be good to figure out what was causing the deadlock in the first place when an error should have been returned.