util: Stop special-casing trySpawnCommandLine() parse errors
Unlike for plain JS Errors, the message
property of GLib.Errors
is read-only, so the intent to replace it with a nicer message
triggers an Error itself.
We could create a new GLib.Error with the changed message instead, but as it turns out, none of the parse errors contain the technical prefix we want to strip out, so we can simply drop the special-casing altogether.
This is also consistent with spawnCommandLine()
, which never
had special treatment of parse errors.
Closes: #8146 (closed)