fix(checker): handle setting unknown as column

midas/checker/frames/column_methods.py

@@ -117,7 +117,7 @@ class ColumnMethodRegistry(MethodRegistry[Call]):
         # Build signature with new column type and generic operand
         param_type: TypeVar = TypeVar(name="T", bound=None)
         signature = GenericType(
-            name="add",
+            name=method,
             params=[param_type],
             body=Function(
                 params=ParamSpec(

midas/checker/frames/frame_manager.py

@@ -132,7 +132,7 @@ class FrameManager:
                 location,
                 f"Cannot assign {type} to dataframe column. Must be a ColumnType",
             )
-            return frame
+            return self._set_column(frame, name, ColumnType(type=UnknownType()))
         return self._set_column(frame, name, type)
 
     def get(