flake: TestAIGatewayKeysTableConstraints (race on shared err) #25979

Seen on PR #25928 in test-go-race-pg:

https://github.com/coder/coder/actions/runs/26822469196/job/79080628504?pr=25928

Failing subtests:

• TestAIGatewayKeysTableConstraints/name_with_underscore
• TestAIGatewayKeysTableConstraints/name_longer_than_64_characters
• TestAIGatewayKeysTableConstraints/duplicate_name

Root cause

err is declared once in the outer test function at coderd/database/querier_test.go:14749 (_, err := db.InsertAIGatewayKey(ctx, preExsiting)) and then reassigned with = inside each parallel subtest at line 14831:

for _, tc := range tests {
    t.Run(tc.name, func(t *testing.T) {
        t.Parallel()

        ctx := testutil.Context(t, testutil.WaitShort)

        _, err = db.InsertAIGatewayKey(ctx, tc.params) // shared `err` from outer scope
        require.Error(t, err)
        requireAIGatewayKeysViolation(t, err, tc.expectUniqueErr, tc.expectCheckErr)
    })
}

All parallel subtests share the outer err. The race detector report points exactly at this:

WARNING: DATA RACE
Write at 0x00c000dc2ad0 by goroutine 855:
  ...TestAIGatewayKeysTableConstraints.func1()
      coderd/database/querier_test.go:14831 +0x144

Previous read at 0x00c000dc2ad0 by goroutine 846:
  ...TestAIGatewayKeysTableConstraints.func1()
      coderd/database/querier_test.go:14833 +0x1c7

Fix

Change _, err = ... to _, err := ... on line 14831 so each subtest gets its own err.

Provenance

Introduced by 32aee9ea4c feat: add DB queries for ai_gateway_coderd_keys (#25564).

_{Filed by Coder Agents on behalf of @Emyrk.}