Update custom_signatures_export.py

Author: mkumykov

examples/custom_signatures_export.py

@@ -146,6 +146,8 @@ def main(argv=None): # IGNORE:C0111
         ### handle keyboard interrupt ###
         return 0
     except Exception as e:
+        import traceback
+        traceback.print_exc()
         if DEBUG or TESTRUN:
             raise(e)
         indent = len(program_name) * " "