Help :S I'm confused by fake errors between VS2019 and UE4.23 during the programming studying

Excuse me. I’m a newbie and studying the basic usage of UE4. I found a confusing situation during the studying in chapter… urr… that “quick programming” chapter.

I’d follow this info and input the code correctly into Visual Studio 2019. Double checked, no mistake.
It ran smoothly. No error nor warning appear and everything goes as predicted. Seems fine.

But when I turn back to VS2019, I saw several error identifier in my code. Just like that 2nd picture.
When I hover them, they kept telling me they are “unidentified” or “class incomplete”.

Surely it can work as normal in UE4. But it will mix into the regular VS error check message and create huge confusing and chaos when I fix codes later, makes me hard to see where the real problem is.

Any idea why and how this happening and how could I stop those fake error identifiers spawning?

Thanks. :open_mouth:

However, it does can complete compiling.

Include header file that error-type has. Unreal use unity build by default for compiling, so missing some include maybe ok.

unity build