New: No longer ignore None results during constraint evaluation (#290)

src/fandango/constraints/base.py

@@ -217,10 +217,10 @@ def fitness(
             )
             try:
                 result = self.eval(self.expression, self.global_variables, local_variables)
-                if result is None:
-                    # This is there to accomodate "constraints" that simply call `print()` (or otherwise produce no value)
-                    # We treat these as "perfect fitness" because they are not actually constraints
-                    return ConstraintFitness(1, 1, True)
+                # Commented this out for now, as `None` is a valid result
+                # of functions such as `re.match()` -- AZ
+                # if result is None:
+                #     return ConstraintFitness(1, 1, True)
                 if result:
                     solved += 1
                 else: