issue #509: raise Listen::Error::INotifyMaxWatchesExceeded rather than abort

[ColinDKelley]

Fix for issue #509:

• When iNotify max watchers exceeded, raise INotifyMaxWatchesExceeded rather than abort.

[ColinDKelley]

BTW, I'm expecting to release this in v3.7.0 in the coming week.

[ioquatix]

It looks okay to me. However, I'm not sure if the exception message needs to be so elaborate?

[ColinDKelley]

@ioquatix I carried the exception across from the old warning message. I like that it points to the documentation.
How would you simplify it? Were you thinking of putting it all on one line maybe? And maybe drop some superfluous words like FATAL and error?
How about:

Listen gem unable to monitor directories for changes because iNotify max watches exceeded. See: #{README_URL}

[ioquatix]

I think the exception message shouldn't contain documentation. So, I'd just say "Max watches exceeded!".

Personally, I don't mind either approach, but if you start adding URLs to exception messages, surely that should apply to all exceptions? So, it's hard to know where to draw the line. Perhaps having documentation on the exception class which explains what to do to mitigate it.

[ColinDKelley]

I don't see any downside to the exception including a link to documentation on how to resolve the problem! The reason we don't do it all the time is that it's a lot of work. ;) In this case, someone before me already did it, and I confirmed that the link still works (since I refactored it into the README a couple months ago) so I think we're good. I will trim it down to the more succinct version, though.