Summary:
When we are using `.*` patterns, this causes an infinite loop. What happens is
we are adding text to the end and then replacing that. Its only when we are
matching the end of the output string.
We can detect this when the starting point is the same as the end point and the
match is "" (an empty string). If we hit this condition we can get out and
return the output that has been replaced.
Test Plan:
Test in CI
Right now we don't want to be panicking if the user provides an invalid regex.
We also don't really want to be throwing or returning an error, this will mess
with any live preview that is going on in external tools.
We should return the input and let any preview display the text. This will
happen if the user is doing some preview as you type kind of thing.
