Return errors for Go Local Vault marshal failures

client.go

@@ -431,13 +431,17 @@ func (c *Client) RevokeLocalVaultInstallation(ctx context.Context, installationI
 
 func (c *Client) RelayLocalVaultEvent(ctx context.Context, installationID string, envelope M, payload M, envelopeHash, signatureHex, publicKeyHex string) (*EventReceipt, error) {
 	body := M{"envelope": envelope, "payload": payload}
+	raw, err := json.Marshal(body)
+	if err != nil {
+		return nil, fmt.Errorf("marshal local vault event: %w", err)
+	}
 	headers := map[string]string{
 		"X-Attesto-Local-Vault-Envelope-Hash": envelopeHash,
 		"X-Attesto-Local-Vault-Signature":     signatureHex,
 		"X-Attesto-Local-Vault-Public-Key":    publicKeyHex,
 	}
 	var out EventReceipt
-	err := c.requestRaw(ctx, http.MethodPost, "/v2/local-vault/installations/"+url.PathEscape(installationID)+"/events", nil, mustJSON(body), headers, "", &out)
+	err = c.requestRaw(ctx, http.MethodPost, "/v2/local-vault/installations/"+url.PathEscape(installationID)+"/events", nil, raw, headers, "", &out)
 	return &out, err
 }
 
@@ -650,14 +654,6 @@ func sleep(attempt int) {
 	time.Sleep(time.Duration(100*attempt) * time.Millisecond)
 }
 
-func mustJSON(value any) []byte {
-	raw, err := json.Marshal(value)
-	if err != nil {
-		panic(err)
-	}
-	return raw
-}
-
 func sanitizeMessage(message string) string {
 	for _, marker := range []string{"sk_live_", "sk_test_", "pk_live_", "pk_test_", "npm_", "pypi-", "atto_live_", "atto_test_"} {
 		if strings.Contains(message, marker) {