effect@4-beta — Schema decode completely broken when transformed by babel-preset-expo (Jest)

[DCKT]

What version of Effect is running?

4.0.0-beta.101

What steps can reproduce the bug?

Every Schema.decode* and Schema.encode* function throws at runtime when the effect package is transformed through babel-preset-expo in Jest. Schema creation and core Effect operations work fine — only the decode/encode pipeline is affected.
This blocks all React Native / Expo projects from upgrading to v4, since jest-expo requires effect in transformIgnorePatterns (effect is ESM-only).

Versions

• effect: 4.0.0-beta.101
• babel-preset-expo: ~57.0.0
• jest: 29.7.0
• Node: 22

Reproduction

Minimal repo: https://github.com/DCKT/effect-v4-babel-bug

git clone https://github.com/DCKT/effect-v4-babel-bug.git
cd effect-v4-babel-bug
yarn install --ignore-engines
yarn test

Config is minimal — the jest config just has transformIgnorePatterns: ["node_modules/(?!effect/)"] and the babel.config.js only uses babel-preset-expo.

What is the expected behavior?

All tests should pass with correct decoding

What do you see instead?

Current behavior (9 tests: 3 pass, 6 fail)

Test	Error
decodeUnknownSync(String)	Cannot read properties of undefined (reading '_tag') at SchemaParser.ts:922
decodeUnknownSync(Struct)	Cannot read properties of undefined (reading 'reasons') at Schema.ts:1413
decodeUnknownSync(decodeTo)	Cannot read properties of undefined (reading '_tag') at Option.ts:85
decodeUnknownExit(String)	Cannot read properties of undefined (reading '_tag') at SchemaParser.ts:922
decodeUnknownExit(Struct)	Cannot read properties of undefined (reading 'reasons') at internal/effect.ts:269
encodeUnknownSync(Struct)	Cannot read properties of undefined (reading 'reasons') at Schema.ts:1413
All 3 passing tests are non-decode operations: Schema.String / Schema.Struct creation and Option.some/none.

Additional information

No response