isArray, vArg not defined.

[bwiggs]

The isArray fallback throws an error when it's used because vArg is undefined.

var utils = {
  isArray: Array.isArray || function() {
    return Object.prototype.toString.call(vArg) === '[object Array]';
  }
};

I've provided a PR to the upstream project with the fix.
brianreavis/microplugin.js#1

[brianreavis]

This is part of the v0.7.6 release. Thanks!