scripts: ssl_session_reset_check: return exception if parsing of preprocessor directive fails

If next(lines) return StopIteration while processing a preprocessor
directive then that's an expected failure that should be reported to
the user.

Signed-off-by: Valerio Setti <[email protected]>

scripts/mbedtls_framework/ssl_session_reset_check.py

@@ -183,7 +183,8 @@ class CStruct:
             try:
                 argument = argument[:-1] + ' ' + next(lines)[1]
             except StopIteration:
-                break
+                raise Exception(f'Unexpected end of the structure reached while '
+                                ' parsing a C preprocessor directive')
         return argument
 
     def _structure_fields(self,