fix(ci): include skin site API error details in failures

scripts/axolotl/publish-skin-site.mjs

@@ -57,12 +57,14 @@ export async function publishSkinSite({
 				continue
 			}
 			if (!response.ok) {
-				await response.body?.cancel()
+				const details = await response.json().catch(() => null)
 				if ((response.status === 429 || response.status >= 500) && attempt + 1 < attempts) {
 					await sleep(500 * (attempt + 1))
 					continue
 				}
-				throw new Error(`Skin site ${route}: HTTP ${response.status}`)
+				throw new Error(
+					`Skin site ${route}: HTTP ${response.status}${typeof details?.errorMessage === 'string' ? ` - ${details.errorMessage.slice(0, 1000)}` : ''}`,
+				)
 			}
 			let result
 			try {

scripts/axolotl/publish-skin-site.test.mjs

@@ -170,3 +170,16 @@ test('CLI emits a GitHub error and exits nonzero when credentials are missing',
 	assert.equal(result.status, 1)
 	assert.match(result.stderr, /::error::.*SKIN_SITE_CI_UPLOAD_TOKEN/)
 })
+
+test('reports structured server errors when creating the upload session fails', async (t) => {
+	const { archivePath } = await fixture(t)
+	await assert.rejects(
+		publishSkinSite(
+			settings(archivePath, {
+				fetch: async () =>
+					Response.json({ errorMessage: 'Upload storage unavailable' }, { status: 500 }),
+			}),
+		),
+		/HTTP 500 - Upload storage unavailable/,
+	)
+})