coredump of language internal function

When creating a function using language internal, if the parameters or function attributes of the alias function are different from those of the internal function, they are not checked during creation and may cause a cordump when called.
a example:
CREATE FUNCTION ftest(integer)
RETURNS numeric
AS 'numeric_in'
LANGUAGE internal
PARALLEL SAFE
STRICT
IMMUTABLE;


I didn't find this mentioned in the manual, so I'm not sure if this is a problem, but it seems like it might be better to do a check when creating the function.