SetOf: revert change to the dimen of empty iterables

pyomo/core/base/set.py

@@ -2634,8 +2634,8 @@ def dimen(self):
                 ans = len(x)
             else:
                 ans = 1
-        except:
-            return None
+        except StopIteration:
+            return 0
         for x in _iter:
             _this = len(x) if type(x) is tuple else 1
             if _this != ans:

pyomo/core/expr/template_expr.py

@@ -1035,7 +1035,7 @@ def __next__(self):
         else:
             d = _set.dimen
         grp = context.next_group()
-        if d is None or type(d) is not int:
+        if not d or type(d) is not int:
             idx = (IndexTemplate(_set, None, context.next_id(), grp),)
         else:
             idx = tuple(