Fix proc-macro panics and wrong context types (#127); clean up macro code (#124)#128

Copilot wants to merge 2 commits intomainHyperCodec/genetic-rs:mainfrom

copilot/fix-macro-bugs-and-add-testsHyperCodec/genetic-rs:copilot/fix-macro-bugs-and-add-testsCopy head branch name to clipboard