`err` was getting nullified when the program terminated abnormally, preventing the regex matching logic from being called.

Should fix binning of abortion caused by SwiftShader debug macros.

Change-Id: I811441296841c77cb87839039cde754d13f2a108
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/39309
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Reviewed-by: Paul Thomson <paulthomson@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Ben Clayton <bclayton@google.com>