Literal::TypeError tweaks and fix for type check in Enum

[stevegeek]

TypeError#deconstruct_keys prob should return all keys when passed nil like Hash say

It is probably not useful to implicitly convert Context to hash so can remove extra to_hash alias (unless we think we might need it)

Enum __after_defined__ still using old TypeError class method so update it to use Literal.check

[joeldrapper]

Another way you could do this is

error = assert_raises(Literal::TypeError) do
  Age.new(17)
end

And then you can continue to make assertions about the error variable.