Parse error: syntax error, unexpected $end in include/validate.inc.php

semi-followup issue to zbx-1999

create item with key "a,+" (without doublequotes), use it in a trigger expression. open trigger, toggle input method, click on 'test'. enter "1" for the value, test :

Parse error: syntax error, unexpected $end in include/validate.inc.php(257) : eval()'d code on line 1