chore(FR-2814): patch relay-runtime to expose full @catch error details

[yomybaby]

Resolves #7246(FR-2814)

Summary

• Patch relay-runtime@20.1.1 so the errors array exposed by @catch fields preserves the full GraphQL error object (message, extensions, etc.) instead of the upstream-stripped subset (path + severity only).
• Patch is registered in pnpm-workspace.yaml under patchedDependencies so it applies automatically for all developers and CI; the patch file lives in react/patches/ next to the existing patches.
• Surface area is intentionally minimal: a single case 'relay_field_payload.error': in RelayReader._asResult is changed to return error.error directly, with an inline comment explaining the deviation from upstream.

Why

Relay 18+ deliberately strips message from the per-field error objects (and never exposes extensions) for PII safety. In our codebase this forces awkward workarounds — e.g. PrometheusQueryTemplatePreview parses the GraphQL error wrapper string via indexOf to recover backend messages. The official escape hatches (relayFieldLogger global side-channel, schema-level error payloads) are either too coarse for component-level UX or require backend changes per call site. We accept the PII trade-off in exchange for a usable error UX in our internal admin tooling.

Test plan

• pnpm install re-applies the patch cleanly (verify a _patch_hash= directory under node_modules/.pnpm/relay-runtime@20.1.1...).
• In a query that uses @catch, when the backend returns a field error, the resulting errors[i] includes message (and extensions when present), in addition to path.
• bash scripts/verify.sh → === ALL PASS ===.

Notes

• TypeScript types in generated artifacts use Result<T, unknown> for the error type, so consumers need to cast at the use site (e.g. errors[0] as { path: readonly (string|number)[]; message?: string; extensions?: Record<string, unknown> }). No type changes are required in this PR.
• Follow-up: replace the indexOf-based message parsing in PrometheusQueryTemplatePreview with direct errors[0].message access (separate PR / Jira issue).

[yomybaby]

• chore(FR-2814): patch relay-runtime to expose full @catch error details #7247 👈 (View in Graphite)
• main

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[Copilot]

Pull request overview

This PR introduces a pnpm patch for relay-runtime@20.1.1 to stop Relay’s @catch per-field error handling from stripping GraphQL error details, so WebUI components can access the full error object (e.g., message, extensions) directly from the errors array.

Changes:

• Add a pnpm patch that changes RelayReader’s handling of relay_field_payload.error to return the full error.error object.
• Register the patch via patchedDependencies so it is applied consistently in developer installs and CI.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
react/patches/relay-runtime@20.1.1.patch	Modifies Relay runtime’s field error mapping to expose the complete GraphQL error object instead of a sanitized subset.
pnpm-workspace.yaml	Registers the new relay-runtime patch under patchedDependencies so pnpm applies it automatically.