Added switch's default option

Signed-off-by: Wonho Yun <[email protected]>

Author: yun-goon

src/dynamixel/dynamixel.cpp

@@ -635,6 +635,8 @@ std::string Dynamixel::DxlErrorToString(DxlError error_num)
       return "DLX_HARDWARE_ERROR";
     case DXL_REBOOT_FAIL:
       return "DXL_REBOOT_FAIL";
+    default:
+      return "UNKNOWN_ERROR";
   }
 }