It looks like the 5.3.0 version of the `FastExpressionCompiler.Internal.src` package is missing a file that is required to let the code compile. Taking a quick look at the package and repo, it appears that it's missing [ILReader.cs](https://github.com/dadhi/FastExpressionCompiler/blob/master/src/FastExpressionCompiler/ILReader.cs). I don't use `FastExpressionCompiler.LightExpression.src`, but it looks like there are problems with it also.