EnC: Changing the type of an expression around an active foreach statement should be a rude edit

[wschae]

1. C# App:

   class Program
   {
       static void Main(string[] args)
       {
           var b = new int[] { 1, 2, 3 };
           foreach (var a in b)
           {
               Console.WriteLine(a); // Add a breakpoint here
           }
       }
   }

2. F5 to stop at the breakpoint
3. Update "int[]" to "double[]" of type of b
4. Continue

Expected: Rude edit saying "cannot edit foreach around an active statement"

Actual: NullReferenceException when stepping into the next iteration of the loop

[wschae]

Ported from internal bug 1009555

[wschae]

Check also 781309 - EnC: Report warning (that local value will be dropped) if local type has changed

[amcasey]

Assigning to @drognanar (fyi @tmat).

[tmat]

Fixed by #74526