= null_denotation ({}, null_denotation_restrictions);

https://github.com/Rust-GCC/gccrs/pull/4417/changes/BASE..0d9c00202fb9490810dbc718a3d66e0b16b5a4d1#diff-cc5073bcead566945869b8222671a22a7e7cf3e91fa23bec9f353384af5bf86fR1797

We recently found a null pointer wrapped within a tl::expected. This is unexpected because we're slowly phasing out null errors in favor of expected.