refactor: TypeScript 6 with full strict mode

[dkastl]

Final piece of the Phase 2 frontend architecture series: the toolchain typechecks the whole bundle under strict: true on TypeScript 6, and CI enforces it.

tsconfig rewrite

The old config described a project that no longer exists: jsx: react, an es6 lib (the source of the long-standing flatMap/Object.entries errors), an unused outDir, and a paths mapping from the webpack era. The new config matches reality, a Vite-bundled browser app typechecked with tsc --noEmit:

• target/lib es2022, moduleResolution: bundler
• strict: true
• skipLibCheck: true (the ol/ol-ext type packages do not pass a strict lib check themselves)

tsc --noEmit went from 16 errors (silently tolerated; nothing ran tsc) to 0, and pnpm typecheck now runs in CI before the build.

Source fixes

All mechanical and behavior-preserving:

• Definite-assignment assertions on GttClient properties, which are populated by the init helpers the constructor calls.
• Explicit this annotations on the remaining instance-bound functions (geocoding, styles).
• Null guards and optional chaining for DOM lookups. The issue-form label scan was copy-pasted five times across geocoding and helpers with a type strict mode rejects; it is now a shared findFieldInput helper.
• getStyle now matches OpenLayers' StyleFunction signature instead of relying on an unsound parameter type.
• Module declarations for the style side-effect imports (a new TS 6 check), and the stale FontFaceSet augmentation left over from the icon-font era is deleted.
• SearchGoogle's default apiKey is '' instead of null (same constructor-time rejection), and initLayers declares the undefined it could already return.

Verification

• pnpm typecheck: 0 errors; pnpm build green.
• Map smoke test in a Redmine 6.1 instance: issue map renders, console clean.
• 39 unit/functional + 3 system tests pass locally against Redmine 6.1-stable, Ruby 3.4, PostGIS 17.

[Copilot]

Pull request overview

This PR upgrades the frontend toolchain to TypeScript 6 and enforces full strict: true typechecking in CI, with a tsconfig rewrite aligned to the current Vite/browser build and a set of strict-mode-driven source fixes across the GttClient OpenLayers/geocoding code.

Changes:

• Rewrites tsconfig.json for a Vite-bundled browser app (ES2022 libs, bundler resolution, strict: true, noEmit) and adds a CI pnpm typecheck gate.
• Updates OpenLayers style/geolocation/edit/layer init code and geocoding/search utilities to satisfy strict mode (explicit this, null guards, corrected signatures).
• Adds/adjusts ambient type declarations for stylesheet side-effect imports and removes stale global font-related typings.

Reviewed changes

Copilot reviewed 14 out of 18 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
tsconfig.json	Updates compiler settings for TS6 + strict typechecking with noEmit and browser/Vite-appropriate targets.
src/components/gtt-client/openlayers/styles.ts	Aligns style function typing with OpenLayers’ StyleFunction signature and adds null-safety.
src/components/gtt-client/openlayers/geolocation.ts	Uses undefined to clear geometries to satisfy stricter typings.
src/components/gtt-client/openlayers/edit.ts	Adds optional chaining for safer geometry access.
src/components/gtt-client/init/layers.ts	Makes initLayers return type reflect existing early-return behavior.
src/components/gtt-client/init/events.ts	Improves DOM query typing via generic querySelectorAll<T>().
src/components/gtt-client/helpers/index.ts	Adds findFieldInput helper and refactors repeated label scans to use it.
src/components/gtt-client/GttClient.ts	Uses definite-assignment assertions and tweaks i18n parsing for strict mode compatibility.
src/components/gtt-client/geocoding/SearchGTT.ts	Adds definite-assignment assertion for a late-assigned button property.
src/components/gtt-client/geocoding/SearchGoogle.ts	Updates defaults and adds strict-mode this typing / non-null assertions.
src/components/gtt-client/geocoding/SearchFactory.ts	Fixes callback typing to match the actual callback payload shape.
src/components/gtt-client/geocoding/index.ts	Adds null guards/optional chaining and reuses findFieldInput in geocoding flows.
src/components/gtt-client/geocoding/CustomButtonMixin.ts	Works around missing typings on ol-ext element helper by casting.
src/@types/custom-fontface-set.d.ts	Removes stale global augmentation.
src/@types/assets.d.ts	Adds ambient module declarations for CSS/SCSS side-effect imports.
package.json	Bumps TypeScript to v6 and adds a typecheck script.
pnpm-lock.yaml	Locks TypeScript v6 resolution.
.github/workflows/test-postgis.yml	Enforces pnpm typecheck in CI before build.

Files not reviewed (1)

• pnpm-lock.yaml: Language not supported

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.