fix crash caused by 39e5008cfc84fe3f88d6e6e75be15241bbd671fe

This is clearly the correct fix, but for testing purposes, it's not clear how to get the index into this weird state. Parsing all of JSDoc will cause a crash while looking at the doclet for module:jsdoc/tag/dictionary.Dictionary. Parsing just lib/jsdoc/tag/dictionary.js seems to work fine.