extend_schema: missing raise statement

Author: Cito

src/graphql/utilities/extend_schema.py

@@ -70,7 +70,7 @@ def extend_schema(
     assert_schema(schema)
 
     if not isinstance(document_ast, DocumentNode):
-        "Must provide valid Document AST"
+        raise TypeError("Must provide valid Document AST")
 
     if not (assume_valid or assume_valid_sdl):
         from ..validation.validate import assert_valid_sdl_extension