Wikimedia Bugzilla is closed!

(Semantic MediaWiki 1.5.6 running on MediaWiki 1.17.0)

1. Have this in LocalSettings.php:

$smwgIgnoreQueryErrors = false

2. Create a page Test with these contents:
{{#ask:[[Has incorrect type::]]|format=count}}

(Any property works as long as the value is empty)

This will result in a catchable fatal error:

Object of class SMWQueryResult could not be converted to string in /var/www/p13.itawiki.org/w/extensions/SemanticMediaWiki-1.5.6/includes/SMW_QueryProcessor.php on line 319

The problem is that the code in SMWQueryProcessor::getResultFromQuery assumes that the output of $store->getQueryResult( $query ) (line 293) is a string when $query->querymode == SMWQuery::MODE_COUNT, and at line 319:

return $res . smwfEncodeMessages( $query->getErrors() );

$res is an integer here, so this obviously fails.

Obviously, it is a syntax error having an empty property value like that, but it's going to happen in templates when people put {{{whatever|}}} as the value.