re-order ALTS log messages.

src/core/tsi/alts/handshaker/alts_handshaker_client.cc

@@ -116,12 +116,13 @@ void alts_handshaker_client_handle_response(alts_handshaker_client* c,
             "cb is nullptr in alts_tsi_handshaker_handle_response()");
     return;
   }
-  if (handshaker == nullptr || recv_buffer == nullptr) {
+  if (handshaker == nullptr) {
     gpr_log(GPR_ERROR,
-            "Invalid arguments to alts_tsi_handshaker_handle_response()");
+            "handshaker is nullptr in alts_tsi_handshaker_handle_response()");
     cb(TSI_INTERNAL_ERROR, user_data, nullptr, 0, nullptr);
     return;
   }
+  /* TSI handshake has been shutdown. */
   if (alts_tsi_handshaker_has_shutdown(handshaker)) {
     gpr_log(GPR_ERROR, "TSI handshake shutdown");
     cb(TSI_HANDSHAKE_SHUTDOWN, user_data, nullptr, 0, nullptr);
@@ -133,6 +134,12 @@ void alts_handshaker_client_handle_response(alts_handshaker_client* c,
     cb(TSI_INTERNAL_ERROR, user_data, nullptr, 0, nullptr);
     return;
   }
+  if (recv_buffer == nullptr) {
+    gpr_log(GPR_ERROR,
+            "recv_buffer is nullptr in alts_tsi_handshaker_handle_response()");
+    cb(TSI_INTERNAL_ERROR, user_data, nullptr, 0, nullptr);
+    return;
+  }
   grpc_gcp_handshaker_resp* resp =
       alts_tsi_utils_deserialize_response(recv_buffer);
   grpc_byte_buffer_destroy(client->recv_buffer);