webfont:ligatures task aborts with "pattern.indexOf"

[remino]

With grunt-webfont 1.7.1, I enabled ligatures in my Gruntfile.js. Yet running grunt --force webfont will create the fonts, but will fail at doing ligatures with the following:

Running "webfont:ligatures" (webfont) task
Verifying property webfont.ligatures exists in config...OK
Warning: pattern.indexOf is not a function Used --force, continuing.  

In the generated icons.html file, I tried enabling ligatures via CSS by adding font-feature-settings: "liga" and I tried writing the name of an icon, but this had no effect. Ligatures are not added to the font file.

[remino]

Dumb me who skimmed README.md added the ligatures: true option directly in the webfont config object in Gruntfile.js instead of putting it in webfont.icons.options. Now it's working.