This pre-release for 4.1.0 shrinks our bundle size via tooling updates, and updates several error messages for clarity. This is all the changes we plan to have for 4.1, so if feedback looks good, we'll release 4.1.0 shortly.

Changelog Summary

The 4.1.0 release will have a more complete changelog, but summarizing:

• Shrinks our bundle sizes by extracting error messages from production builds and replacing them with error codes (similar to React). Thanks to @andrewmcgivery for implementing this!
• Inlines the symbol-observable polyfill
• Drops the legacy loose-envify dependency
• Externalizes the @babel/runtime helpers
• Fixed a TS typedef to work better with TS 4.3

We've also updated the error messages to clarify what's happening, provide more details when runtime type checks fail, and link to relevant documentation.

Changes

• Merge pull request #4058 from reduxjs/feature/4x-remove-legacy-deps 9a1d065
• Inline the symbol-observable polyfill 0d7d94d
• Remove symbol-observable and loose-envify deps b882d9a
• Merge pull request #4057 from reduxjs/feature/4x-error-messages f3680b5
• Port error message updates from master 46f5c94
• Port error extraction setup from master 05d5505
• Merge pull request #4056 from reduxjs/feature/4x-update-build-tooling 82ad636
• fix: Declare "EmptyObject" interface to wrap $CombinedState (#4031) c3cbe2e
• Only apply mapped types to un-branded types (#3805) e23aa59

v4.0.5...v4.1.0-alpha.0