in src/Collection.js [40:54]
constructor(paths, parent, types) {
assert.ok(Array.isArray(paths), 'Collection is passed an array');
assert.ok(
paths.every(p => p instanceof NodePath),
'Array contains only paths'
);
this._parent = parent;
this.__paths = paths;
if (types && !Array.isArray(types)) {
types = _toTypeArray(types);
} else if (!types || Array.isArray(types) && types.length === 0) {
types = _inferTypes(paths);
}
this._types = types.length === 0 ? _defaultType : types;
}