If there's a existing issue, please link to it. If not, provide fill out the same information you would in a normal issue - reproduction steps for bugs, rationale for use-case.
If you're working on CraftOS, try to write a few test cases so we can ensure everything continues to work in the future. Tests live in src/test/resources/test-rom/spec and can be run with ./gradlew check.
A quick checklist
src/test/resources/test-rom/specand can be run with./gradlew check.