State errors display in ProB2UI not very readable and sometimes fails

[leuschel]

The display of state errors (in particular WD errors) is not very user friendly and seems to fail for this example here.
In Tcl/Tk you also have the option to visualise some errors (i.e., get a graphical formula tree explaining the cause of the error).

[dgelessus]

The "Sorry, the detailed output failed." message appears quite often. It comes from the Prolog side - see explain_state_error/3 in translate.pl. There's probably a bug somewhere there that breaks the detailed error output.

[leuschel]

There was a bug in prob2_interface:convert_errors which
was setting the Span to unkonwn.
Fixed in 503b361334a0feb2cf19ec9add9f47a02487bee3
But we should probably use this span in some way, I think Tcl/Tk uses it for the Visualize button if the span contains a span predicate.

[leuschel]

The call stack (if available) is now also shown in the ProB2UI view