Fix for jsmin not returning errors

Problem/Motivation

I have a JS file not being compressed by jsmin but no errors at watchdog. Parsing errors returned by jsmin do not trigger exceptions.
As shown at https://github.com/sqmk/pecl-jsmin there are extra args and error functions to manage errors from jsmin.

Proposed resolution

You can keep the try / catch to trigger exceptions, it works. But I suggest to add an extra control: jsmin_last_error() / jsmin_last_error_msg() to discover other parsing errors

I tried to make a fast patch using TortoiseGitMerge (from Win) but patch file includes my full local path. I will try to fix the path by hand.

Please check and give me feedback.

Thanks