Null deref?
Like, some `switch` construct got optimized into kind of `foo[bar].doCrap(ctx, data)` construct? But the `foo[bar]` kind of construct without default pathway can happen in Rust anyway if that thing constructed dynamically (e. g. by other earlier part of arriving data).
this can be a common situation for some "rules engine" or other high-level code execution branching infrastructure.
Does Rust can enforce "always have a meaningful result for `foo[bar]` construct?