Strange errors caused by the compilation of LINQ

Today, I encountered a very strange problem. I initially guessed that it was the cause of the compilation of LINQ and the automatic optimization of the compiler. I am not very familiar with IL, so I am too lazy to catch up with it.

Paste a piece of code to get a positive solution.

 

I noticed that I used the original foreach statement instead of the LINQ query. If LINQ is used, a null reference error is returned when var Arg = jsonconvert. deserializeobject <loadhallarg> (requestinfo. Body) is run.

VaR Arg = jsonconvert. deserializeobject <loadhallarg> (requestinfo. Body );

// Var Hall = testdatacenter. Hils. firstordefault (O => O. hallid = others. hallid );

Hall = NULL;

Foreach (VAR hl in testdatacenter. Hils)

{
If (HL. hallid = Arg. hallid)
{
Hall = HL;
Break;
}
}

 

Strange errors caused by the compilation of LINQ