Is https://docs.rs/web-sys/latest/web_sys/struct.DedicatedWorkerGlobalScope.html#method.set_onmessage quite unsafe to use?

[zeroexcuses]

Links:

• DedicatedWorkerGlobalScope in web_sys - Rust

• wasm-bindgen/lib.rs at e4477293c15df8500330b295cb9624dccb2a063b · rustwasm/wasm-bindgen · GitHub [actually for webrtc, not DedicatedWorkerGlobalScope]

The point here is: to use these set_onmessage functions safely, are we supposed to call .forget() afterwards (or by some other means ensure that the callback stays vaild)?

Why is this not unsafe ?