The problem is when you do something like:
```javascript
$('.banana', fruits).next();
```
This will happen:
```javascript
var next = exports.next = function() {
  var elem = this[0]; // elem will be undefined now
  while ((elem = elem.next)) if (isTag(elem)) return this.make(elem); // error, trying to hit .next of undefined
  return this.make([]);
};
```
This should fix it:
```javascript
var next = exports.next = function() {
  if (!this[0]) { return this; } // this[0] is undefined, and false-y, so it will just return this; an empty object
  var elem = this[0];
  while ((elem = elem.next)) if (isTag(elem)) return this.make(elem);
  return this.make([]);
};
```