fix: type nullable TypeScript model properties as T | null

[ChiragAgg5k]

Closes #2021

What

The TypeScript SDKs (web, node, react-native, deno) typed nullable: true model properties as optional only (passwordPwned?: boolean). The API documents and returns null for these, so under strictNullChecks the real value couldn't be represented. Every other SDK already encodes it (Bool?, bool?, *bool, ?bool, Optional[bool], Option<bool>).

Nullable properties now render as T | null. Optional non-nullable properties stay ?: T.

passwordPwned?: boolean | null;

This applies to response models and request models in all four TS SDKs.

How

• tsModelProperty takes a nullable flag, so the formatter sees the full type when deciding on line breaks. Generated code has to be Prettier-clean already, and Prettier 3.9.6 lays out an overflowing T | null in one of three ways. I checked each layout against Prettier directly:
  • break after the colon when T | null fits on the next line (plain names, arrays and union arrays)
  • leading pipes for a union array that doesn't fit, expanding the inner union when that overflows too
  • left on one line otherwise (generics, or nothing fits)
• web/src/models.ts.twig, react-native/src/models.ts.twig and node/src/models/requestModel.ts.twig pass property | schemaNullable. deno/src/models.d.ts.twig appends | null.

Release note

Widening a property's type breaks source compatibility for strict TypeScript consumers whose reads assumed T | undefined. This should ship in the next major of each TS SDK.

Tests

One shared e2e line that every SDK prints:

• The fixture preset model gains an optional nullable verified boolean. The mock server's GET /mock/tests/general/preset returns it as null.
• New Base::NULLABLE_MODEL_RESPONSES (preset verified: null) sits next to MODEL_DEFAULT_RESPONSES in every e2e class that uses it (all 33). Each language program prints the decoded value: apple, swift, android, kotlin, dart, flutter, dotnet, unity, go, go-v2, php, python, ruby, rust, node, web (node and chromium), react-native and deno. This also covers decoding of an explicit null in every SDK.
• JS_MODEL_TO_STRING_RESPONSES now includes "verified":null, so the JS SDKs keep the null through toString().
• The Deno program reads the value through Models.Preset["verified"] and assigns null to it, so Deno 1.19 (which type-checks on deno run) fails to compile without this fix.

Verification

• e2e run locally and passing: PHP85, Python313, Go118, Ruby31, Node20, Deno1303, WebNode. CI covers the rest.
• npm run format:check, lint and analyse pass on web (client), node (server, including npm test) and react-native (client), generated from the live 2.4.x spec. The diff touches 303 node model properties and adds only | null.
• The overflow layouts were checked by generating node from a scratch spec with long nullable names, arrays and union arrays, then running prettier --check.
• The Generation suite, composer lint, composer refactor:check and composer lint-twig all pass.