catch json error (#660)

cashu/wallet/wallet_deprecated.py

@@ -1,3 +1,4 @@
+import json
 from posixpath import join
 from typing import List, Optional, Tuple, Union
 
@@ -106,7 +107,12 @@ def raise_on_error(
         Raises:
             Exception: if the response contains an error
         """
-        resp_dict = resp.json()
+        try:
+            resp_dict = resp.json()
+        except json.JSONDecodeError:
+            # if we can't decode the response, raise for status
+            resp.raise_for_status()
+            return
         if "detail" in resp_dict:
             logger.trace(f"Error from mint: {resp_dict}")
             error_message = f"Mint Error: {resp_dict['detail']}"