[solved somehow]"object reference not set to an instance of an object" when try to build tmx/tsx file in the MGBC editor

I’m new on C# and monogame.
The tsx file was embedded form, but when i tried to build my tmx and tsx files in MGBC editor, there are still 2 building failed. Both problem is this:

And maybe because of this, when i try to run my project, VS2022 shows these problem:

Wondering how to fix this.

Luckily, the TiledSharp is still workable. So there is no problem now.