Also change several error messages to refer to "items" rather than
"methods", since associated items that require resolution during type
checking are not always methods.
check::autoderef() returns a ty_err when it fails to infer the type.
probe::probe() should respect this failure and fail together to prevent
further corruption.
Call stack: check::check_method_call() -> method::lookup() ->
probe::probe() + confirm::confirm()
Fixes#19692.
Fixes#19583.
Fixes#19297.
