IF

• a activated plugin is providing a scripting function
• and this scripting function is used in scripting
• and the user goes to Options > Plugins and disables the plugin, then saves options without removing the scripting function from scripts

THEN

• when scripts are applied Picard will crash

Traceback (most recent call last):
File "./picard/coverart/_init_.py", line 142, in next_in_queue
provider = next(self.providers)
StopIteration

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "./picard/webservice/_init_.py", line 442, in _process_reply
self._handle_reply(reply, request)
File "./picard/webservice/_init_.py", line 431, in _handle_reply
handler(reply.readAll(), reply, error)
File "./picard/coverart/_init_.py", line 121, in _coverart_downloaded
self.next_in_queue()
File "./picard/coverart/_init_.py", line 158, in next_in_queue
self.next_in_queue()
File "./picard/coverart/_init_.py", line 158, in next_in_queue
self.next_in_queue()
File "./picard/coverart/_init_.py", line 158, in next_in_queue
self.next_in_queue()
[Previous line repeated 2 more times]
File "./picard/coverart/_init_.py", line 162, in next_in_queue
self.album._finalize_loading(None)
File "./picard/album.py", line 335, in _finalize_loading
parser.eval(s_text, track.metadata)
File "./picard/script.py", line 294, in eval
return ScriptParser._cache[key].eval(self)
File "./picard/script.py", line 133, in eval
return "".join([item.eval(state) for item in self])
File "./picard/script.py", line 133, in <listcomp>
return "".join([item.eval(state) for item in self])
File "./picard/script.py", line 124, in eval
args = [arg.eval(parser) for arg in self.args]
File "./picard/script.py", line 124, in <listcomp>
args = [arg.eval(parser) for arg in self.args]
File "./picard/script.py", line 133, in eval
return "".join([item.eval(state) for item in self])
File "./picard/script.py", line 133, in <listcomp>
return "".join([item.eval(state) for item in self])
File "./picard/script.py", line 122, in eval
function, eval_args, num_args = parser.functions[self.name]
KeyError: 'replace_forbidden'
zsh: abort (core dumped) ./tagger.py test/data/test.wav

The crash does not happen again if the plugin is disabled already on start. In this case applying the script will just raise

picard.script.ScriptUnknownFunction: Unknown function 'replace_forbidden'
E: 07:55:41,622 album._finalize_loading:337: Failed to run tagger script Test replace_forbidden on track