Fix TextInput's is_persistent() flow

discord/ui/select.py

@@ -162,10 +162,10 @@ class BaseSelect(Item[V]):
     @custom_id.setter
     def custom_id(self, value: str) -> None:
         if not isinstance(value, str):
-            raise TypeError('custom_id must be None or str')
+            raise TypeError('custom_id must be a str')
 
         self._underlying.custom_id = value
-        self._provided_custom_id = value is not None
+        self._provided_custom_id = True
 
     @property
     def placeholder(self) -> Optional[str]:

discord/ui/text_input.py

@@ -137,10 +137,11 @@ class TextInput(Item[V]):
     @custom_id.setter
     def custom_id(self, value: str) -> None:
         if not isinstance(value, str):
-            raise TypeError('custom_id must be None or str')
+            raise TypeError('custom_id must be a str')
 
         self._underlying.custom_id = value
-
+        self._provided_custom_id = True
+        
     @property
     def width(self) -> int:
         return 5