Restore error message for a macro with unbalanced parentheses.

Restore error message for a macro with unbalanced parentheses.

We had to remove this earlier because our recursive function calls
caused the same nodes to be examined for expansion more than once.
And in the test suite, one node would be examined before it had
its closing parenthesis and then again later after the parenthesis
was added.

So we removed this error message to allow the test case to pass.
Now that we've removed the unnecessary recursive function call
we can catch this error case and report it as desired.