Fix a jQuery 3 incompatibility

[mpavey0]

The selector property was dropped from jQuery 3 (see:
https://api.jquery.com/selector/).

In this instance (the removeError method), there is no need
for it in the first place. Instead, we can just use the
jQuery object provided (node).

[mpavey0]

Hi @running-coder , seems fairly clear you're no longer actively developing this so not sure whether this PR is helpful but I figured I'd send it over. I'm upgrading my site to jQuery 3 and found some incompatibilities in your library. This was a fairly easy fix, though it looks like there are lots of other instances of node.selector still present which probably require more careful thought.

I didn't attempt to build the dist versions, looks like you may have some custom steps in place to remove the debug code, comments, etc.?

Looks like you removed the Issues section from the Github repo? 😢 I know you mentioned you had planned to rewrite the library in ES6 soon…any updates on that? 😉