Ensure stderr is piped to stdout to capture errors in output

tests/shell_commander/test_shell_commander.c

@@ -17,8 +17,8 @@ TestFuncResult test_commander_cmd_success(void) {
 }
 
 TestFuncResult test_commander_cmd_failure(void) {
-  CMDResult result = wapp_shell_commander_execute(SHELL_OUTPUT_DISCARD, NULL, 0,
-                                                  "grep", "2>&1");
+  CMDResult result =
+      wapp_shell_commander_execute(SHELL_OUTPUT_DISCARD, NULL, 0, "grep");
 
   bool failed = result.exited && result.exit_code != EXIT_SUCCESS &&
                 result.error == SHELL_ERR_NO_ERROR;