Add error handling and fallback for .filter

[danielravina]

I use fuzzy on a backend project where the pattern and the arr are sometimes undefined or empty. Thought it'll be good to have some error handling and fallbacks. Without it, when you pass undefined, it breaks:

# When pattern is undefined
TypeError: Cannot read property 'toLowerCase' of undefined`
# When arr is undefined
TypeError: Cannot read property 'reduce' of undefined

[mattyork]

Awesome! Thanks for the PR

[danielravina]

all fixed! :+1:

[danielravina]

Thanks. Any eta for release on npm?