Per the discussion in #230 (comment), this is a tracker issue for a general refactor:

• Target Node 14 and update dependencies (Separate index.js and test.js into different files #234)
• Separate index.js into separate source files (Separate index.js and test.js into different files #234)
  • Separate tests into smaller files/fixtures, maybe consolidate via macros
  • Not directly related, but adding subcommands (Support subcommands #69) benefits from this
• Target Node 16 and use new features (Target Node 16 #235)
• Bundle dependencies (Bundle dependencies #67, Use Rollup for bundling dependencies #242)
• Ensure that documentation / terminology is consistent across the project
  • Improve error messages - consistent format, make sure all cases are covered
  • Potentially add JSDoc comments to source functions
• Look into lazy loading cli.pkg (Optimize startup performance #104)
• Add tests where missing, if needed
• Improve documentation surrounding importMeta (Make options required #260)
  • The readme doesn’t say that it’s required (Improve importMeta message -meow - The 'importMeta' option is required. Its value must be 'import.meta' at meow #222 (comment))
• Rewrite in TypeScript (Rewrite in TypeScript #252)