make corpus-download fetches a 404 page for google-maps-platform.json

[erraggy]

Summary

The Google Maps URL in make corpus-download (Makefile:450) now 404s. curl -sL writes the error body to the target path, so the corpus ends up with a 14-byte file containing the literal text 404: Not Found:

14 testdata/corpus/google-maps-platform.json

cat testdata/corpus/google-maps-platform.json
# 404: Not Found

The URL is:

https://raw.githubusercontent.com/googlemaps/openapi-specification/main/dist/google-maps-platform-openapi3.json

Impact

SkipIfNotCached only checks whether the file exists, not whether it is a valid spec, so a 14-byte HTTP error body counts as "cached". Corpus tests for GoogleMaps then fail on unparseable content rather than skipping cleanly. Deleting the file produces the correct skip.

Suggested fix

Two parts, the second being the more valuable:

1. Find the spec's current location (the googlemaps/openapi-specification repo may have moved or renamed dist/), or drop GoogleMaps from the corpus if it is gone for good.
2. Make corpus-download fail loudly instead of silently writing error bodies — curl -sL --fail returns non-zero on 4xx/5xx and writes nothing, which would have surfaced this at download time rather than as a confusing test failure later. Worth applying to every URL in the target, not just this one.

Found on 2026-07-27 while preparing v1.57.0. Related: #400 (corpus specs are live and gitignored, so CI never exercises this path).

[erraggy]

Duplicate of #391, which covers the same 404, the same missing --fail root cause, and the same fix — and does it more thoroughly, enumerating the four affected tests across validator/fixer/generator and suggesting a post-download parse smoke test.

Closing this one. Filed without searching existing issues first; #391 is the tracking issue.

One cross-reference now that it exists: #391 notes the USNWS make check failure as "a separate pre-existing issue" — that is now tracked as #400.