Resolves #1790 - use e.is_a? instead of e.message

[egeek]

Switching to checking if the exception is a name error reduces the processing time for cases where a client application has extended how the exception processing works

[carlosantoniodasilva]

Thanks @egeek, we're going to try an approach that doesn't rely on exception rescuing, but checks for const_defined? first: #1810. Let's see how it goes. it's on main now, let us know if that causes you any issues.

[carlosantoniodasilva]

I'm reverting the merged change, as it caused a regression. See #1824 for more info.

Happy to review something else that fixes the original problem without the regression, but for now we'll have to live with it.