Default to string when we don't understand the format. (#2588)

Author: jack-edmonds-dd

.generator/src/generator/formatter.py

@@ -152,11 +152,9 @@ def simple_type(schema, render_nullable=False, render_new=False):
         return {
             "date": "time.Time" if not nullable else f"{nullable_prefix}Time",
             "date-time": "time.Time" if not nullable else f"{nullable_prefix}Time",
-            "email": "string" if not nullable else f"{nullable_prefix}String",
             "binary": "_io.Reader",
             "uuid": "uuid.UUID" if not nullable else f"{nullable_prefix}String",
-            None: "string" if not nullable else f"{nullable_prefix}String",
-        }[type_format]
+        }.get(type_format, "string" if not nullable else f"{nullable_prefix}String")
     if type_name == "boolean":
         return "bool" if not nullable else f"{nullable_prefix}Bool"