Since some time, `stash_group_add_string()` does not set the passed default value to the setting any longer if the setting is not found.
This might be related to cf77c8c0f1f0cc6ad7bf3132ea1d59639a7a83e7.
There is a real implication of this: I noticed crashing Geany when the VTE setting `follow_path` is `true` and `send_cmd_prefix` is not set. This results in `vc->send_cmd_prefix` being `NULL` which then leads to crashes when commands are to be executed in the VTE (it should not crash even then, a fix for the VTE issue will follow).
But the root cause here is that it seems that the passed default `stash_group_add_string()` is ignored.
@kugel-, could you maybe have a look?