That error is caused by the following bit of code in src/plugins.js
paths = paths.map(function(pluginLib) {
var parent = path.dirname(pluginLib);
return cached.filter(function(libPath) {
return libPath.indexOf(parent) !== -1;
});
}).reduce(function(prev, cur) {
return prev.concat(cur);
});
If paths is an empty array calling reduce will throw that error. We should add better checks to detect that.
