Debug: show raw response body to diagnose json() failure

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

1 files changed, 10 insertions, 4 deletions

diff --git a/app/routes/auth.register.tsx b/app/routes/auth.register.tsx
index 7d8fb5d..43e9c71 100644
--- a/app/routes/auth.register.tsx
+++ b/app/routes/auth.register.tsx
@@ -132,12 +132,18 @@ export default function Register() {
         body: JSON.stringify({ token }),
       });
       setStep("1b. fetch 完了 status=" + optRes.status); await tick();
+      const rawText = await optRes.text();
+      setStep("1c. body=" + rawText.slice(0, 120)); await tick();
       if (!optRes.ok) {
-        const err = await optRes.json();
-        throw new Error(err.error ?? "オプション取得に失敗しました");
+        throw new Error("HTTP " + optRes.status + ": " + rawText.slice(0, 200));
       }
-      const optJSON = await optRes.json();
-      setStep("1c. JSON パース OK"); await tick();
+      let optJSON: Record<string, unknown>;
+      try {
+        optJSON = JSON.parse(rawText);
+      } catch (e) {
+        throw new Error("JSON.parse 失敗: " + String(e) + " | body: " + rawText.slice(0, 100));
+      }
+      setStep("1d. JSON パース OK"); await tick();
 
       const userId = b64urlToBuffer(optJSON.user.id);
       const challenge = b64urlToBuffer(optJSON.challenge);