Update Error message's when passing nil args when initializing a Date

[dannyd4315]

This PR fixes an issue with Date and passing nil arguments when initializing a Date. The issue is explained here - https://bugs.ruby-lang.org/issues/15298

Current behaviour

Date.new(1999, 1, 32)   # => ArgumentError: invalid date

If you provide nil as any of the three arguments, you do not get this error. You get three unrelated errors (two NoMethodErrors and one TypeError), none of which are specific to date:

Date.new(1999, 1, nil)  # => NoMethodError: undefined method `div' for nil:NilClass
Date.new(1999, nil, 32) # => TypeError: no implicit conversion from nil to integer
Date.new(nil, 1, 32)    # => NoMethodError: undefined method `<' for nil:NilClass

New behaviour

Date.new(1999, 1, 32)   # => ArgumentError: invalid date
Date.new(1999, 1, nil)  # => ArgumentError: invalid date
Date.new(1999, nil, 32) # => ArgumentError: invalid date
Date.new(nil, 1, 32)    # => ArgumentError: invalid date

[jeremyevans]

It seems odd to me to only attempt to handle nil values specially. Shouldn't Date.new(Object.new, 1, 1) raise the same exception as Date.new(nil, 1, 1)? Additionally, if we are going to check that the types do not match, TypeError seems to be a better error to raise than ArgumentError. Maybe we should try converting all values to integer, so we get:

Date.new(1999, 1, nil)  # => TypeError: no implicit conversion from nil to integer
Date.new(1999, nil, 1) # => TypeError: no implicit conversion from nil to integer
Date.new(nil, 1, 1)    # => TypeError: no implicit conversion from nil to integer

That seems to be more consistent with the core classes:

Array.new(nil)
"" * nil
[1,2,3][1, nil]

[shyouhei]

It seems ruby/date#9 is related.