patch 9.1.1195: inside try-block: fn body executed with default arg undefined

patch 9.1.1195: inside try-block: fn body executed with default arg undefined

Problem:  inside try-block: fn body executed when default arg is
          undefined
Solution: When inside a try-block do not execute function body after an
          error in evaluating a default argument expression
          (Shane Harper).

closes: #16865

Signed-off-by: Shane Harper <shane@shaneharper.net>
Signed-off-by: Christian Brabandt <cb@256bit.org>