Fix failure to report blockfrost error when cbor decode fails

Author: kieransimkin

pycardano/backend/blockfrost.py

@@ -310,8 +310,13 @@ def evaluate_tx_cbor(self, cbor: Union[bytes, str]) -> Dict[str, ExecutionUnits]
             cbor = cbor.hex()
         with tempfile.NamedTemporaryFile(delete=False, mode="w") as f:
             f.write(cbor)
-        result = self.api.transaction_evaluate(f.name).result
+        
+        result = self.api.transaction_evaluate(f.name)
         os.remove(f.name)
+        if not hasattr(result, "result"):
+            raise TransactionFailedException(result)
+        else:
+            result = result.result
         return_val = {}
         if not hasattr(result, "EvaluationResult"):
             raise TransactionFailedException(result)