Repro steps:

Just access a property of the globals object:

#! "netcoreapp2.0"
var x = Args.FirstOrDefault();

Expected Result

No Error.

Actual Result

Note that Linq itself works correctly. For example, the following code works fine:

#! "netcoreapp2.0"
var x = new List<string> {"a"};
var y = x.FirstOrDefault();