The very same type of mistakes happens in file systems even without URIs being involved. Directory traversal checks look simple but sooner or later need hard-to-understand symlink following rules. Enforcing processor policy has terrible portability there (it even only became practical on Linux with landlock), but nonetheless I think it's preferable.
Not mixing URI parsers is a good advice for when processor policies are unavailable – but let's try to make them available more often.

@snaggen I think the better lesson than "don't mix URI parses" here is "don't LBYL, rely on EAFP". Many "Look before you leap" (LBYL) schemes are subject to variations of time-of-check/time-of-use errors. It's preferable to not sanitize input, but tell the processor what the policy on processing is; when it comes to a violation, it's easier to ask forgiving (i.e. report the error) than permission (EAFP).

@0xsaksham @snaggen Last polls I saw, the #RustLang hashtag (it's case sensitive, but capitalization helps for accessibilisy) was a tad more popular than #Rust due to the latter's ambiguities.

@jvisick That process is completely intransparent to anyone approaching this without preexisting knowledge of that Lemmy instance. Do you know who runs that account? They should really make a note in its metadata.

Coroutines are one means of implementing async; the way they are implemented in Rust is more like building a state machine out of the async function. It can still be mapped to coroutines, and there are probably crates that use async and macros to make coroutines usable on stable, but the effort to have a stable language feature is still ongoing, with https://lang-team.rust-lang.org/design_notes/general_coroutines.html giving the overview.