Issuing a warning causes an error

[MJRinne]

The issue manifests at least when trying to INSERT an unbound variable.

Steps to reproduce:

1) Query (issue1.rq):

PREFIX : http://instans.org/

INSERT { ?sub ?pred ?obj } WHERE { BIND (:sub2 as ?sub) OPTIONAL { ?sub ?pred ?obj } }

2) Data (issue1.ttl):

@prefix : http://instans.org/ .

:sub :pred :obj .

3) Command line: $ instans -r issue1.rq -t issue1.ttl

What happens:

Execution is terminated, the triple with unbound variables is not inserted, the following message is printed:

Warning: RDFterm-equal: Cannot apply to arguments (#<SPARQL-UNBOUND {10006DEA13}> #<SPARQL-UNBOUND

                                                                       {10006DEA13}>)

debugger invoked on a SB-INT:SIMPLE-CONTROL-ERROR in thread

<THREAD "main thread" RUNNING {10052639C3}>:

attempt to THROW to a tag that does not exist: :SPARQL-ERROR

Type HELP for debugger help, or (SB-EXT:EXIT) to exit from SBCL.

(no restarts: If you didn't do this on purpose, please report it as a bug.)

("no debug information for frame") 0]

What was expected to happen:

Warning shown, execution continued.

Relations to other issues:

This condition should not trigger a warning, reported as issue#2. This issue should be fixed before #2, otherwise a new example of this issue will be needed.

[MJRinne]

Issue #2 got fixed before checking this one - to be checked when a suitable case causing a warning is available.