Fix the corner cases

[sueka]

I've tried doing

• avoid zero division & zero vector normalization
• prevent an indeterminate form from being generated (by 0.0 / 0.0 )

[Ch4s3]

@sueka Thanks for the PR!

If you can fix NoMethodError: undefined method zero?' for nil:NilClass`, I'll take a closer look.

[sueka]

@Ch4s3

Fixed it. I think there are two ways to fix the NoMethodError: the other is by using safe navigation operator to call zero? method.

[Ch4s3]

This looks pretty good. Can you perhaps add a couple of test cases that would have previously caused zero division & zero vector normalization errors but are handled now?

I hate to keep throwing up barriers, but this is a tricky section of code, so I want to make sure we don't have a regression here.

[Ch4s3]

Again @sueka thanks a ton. Once we get this in I'll roll out a new gem version. I'll try to get this into 2.2.1 with #174 if you can get to this soon, otherwise I'll roll it into2.3 with #162.

[sueka]

I've added tests against zero vector normalization and zero division errors.

[Ch4s3]

Awesome, thanks again for the great contribution!