fix: only cache get requests

[alanshaw]

Adding a HEAD request in another PR and came across this issue.

[olizilla]

What happens if you try and cache a HEAD?

More generally I'd like to flag that I'm finding the withX pattern for workers less easy to work with than just providing simpler getX functions that a given route handler explictly calls rather than the "add deps to a context and assume they are set in a handler" pattern. In this case, magic auto caching is suprising... and it'd also be reasonable to want to cache HEAD responses, which would involve accessing the caches directly and re-writing the request to be a get for the cache, which is, for example, something a route handler should do rather than a withX

[alanshaw]

What happens if you try and cache a HEAD?

Cloudflare throws an error when caching anything not GET.

More generally I'd like to flag that I'm finding the withX pattern for workers less easy to work

ACK, lets open an issue though because this perhaps not the best place to discuss.

"add deps to a context and assume they are set in a handler" pattern

There's no assumptions - every handler defined here checks their dependencies exist.