protected void OnChange (){
      if (change !=null){ //вылетает на этой строке
         change.Invoke ();
      }

Change?.Invoke();

protected void OnChange ()
{
      var change = this.Change;
      if (change != null) {
         change.Invoke();
      }
}

namespace TestProject
{
    public class TestC
    {
        public event EventHandler MyEvent;

        protected void OnMyEvent(EventArgs a)
        {
            MyEvent?.Invoke(this, a);
        }

    }
}

.class public auto ansi beforefieldinit 
  TestProject.TestC
    extends [mscorlib]System.Object
{

  .field private class [mscorlib]System.EventHandler MyEvent
  .custom instance void [mscorlib]System.Runtime.CompilerServices.CompilerGeneratedAttribute::.ctor() 
    = (01 00 00 00 )
  .custom instance void [mscorlib]System.Diagnostics.DebuggerBrowsableAttribute::.ctor(valuetype [mscorlib]System.Diagnostics.DebuggerBrowsableState) 
    = (01 00 00 00 00 00 00 00 ) // ........
    // int32(0) // 0x00000000

  .method public hidebysig specialname instance void 
    add_MyEvent(
      class [mscorlib]System.EventHandler 'value'
    ) cil managed 
  {
    .custom instance void [mscorlib]System.Runtime.CompilerServices.CompilerGeneratedAttribute::.ctor() 
      = (01 00 00 00 )
    .maxstack 3
    .locals init (
      [0] class [mscorlib]System.EventHandler V_0,
      [1] class [mscorlib]System.EventHandler V_1,
      [2] class [mscorlib]System.EventHandler V_2
    )

    IL_0000: ldarg.0      // this
    IL_0001: ldfld        class [mscorlib]System.EventHandler TestProject.TestC::MyEvent
    IL_0006: stloc.0      // V_0
    // start of loop, entry point: IL_0007
      IL_0007: ldloc.0      // V_0
      IL_0008: stloc.1      // V_1
      IL_0009: ldloc.1      // V_1
      IL_000a: ldarg.1      // 'value'
      IL_000b: call         class [mscorlib]System.Delegate [mscorlib]System.Delegate::Combine(class [mscorlib]System.Delegate, class [mscorlib]System.Delegate)
      IL_0010: castclass    [mscorlib]System.EventHandler
      IL_0015: stloc.2      // V_2
      IL_0016: ldarg.0      // this
      IL_0017: ldflda       class [mscorlib]System.EventHandler TestProject.TestC::MyEvent
      IL_001c: ldloc.2      // V_2
      IL_001d: ldloc.1      // V_1
      IL_001e: call         !!0/*class [mscorlib]System.EventHandler*/ [mscorlib]System.Threading.Interlocked::CompareExchange<class [mscorlib]System.EventHandler>(!!0/*class [mscorlib]System.EventHandler*/&, !!0/*class [mscorlib]System.EventHandler*/, !!0/*class [mscorlib]System.EventHandler*/)
      IL_0023: stloc.0      // V_0
      IL_0024: ldloc.0      // V_0
      IL_0025: ldloc.1      // V_1
      IL_0026: bne.un.s     IL_0007
    // end of loop
    IL_0028: ret          

  } // end of method TestC::add_MyEvent

  .method public hidebysig specialname instance void 
    remove_MyEvent(
      class [mscorlib]System.EventHandler 'value'
    ) cil managed 
  {
    .custom instance void [mscorlib]System.Runtime.CompilerServices.CompilerGeneratedAttribute::.ctor() 
      = (01 00 00 00 )
    .maxstack 3
    .locals init (
      [0] class [mscorlib]System.EventHandler V_0,
      [1] class [mscorlib]System.EventHandler V_1,
      [2] class [mscorlib]System.EventHandler V_2
    )

    IL_0000: ldarg.0      // this
    IL_0001: ldfld        class [mscorlib]System.EventHandler TestProject.TestC::MyEvent
    IL_0006: stloc.0      // V_0
    // start of loop, entry point: IL_0007
      IL_0007: ldloc.0      // V_0
      IL_0008: stloc.1      // V_1
      IL_0009: ldloc.1      // V_1
      IL_000a: ldarg.1      // 'value'
      IL_000b: call         class [mscorlib]System.Delegate [mscorlib]System.Delegate::Remove(class [mscorlib]System.Delegate, class [mscorlib]System.Delegate)
      IL_0010: castclass    [mscorlib]System.EventHandler
      IL_0015: stloc.2      // V_2
      IL_0016: ldarg.0      // this
      IL_0017: ldflda       class [mscorlib]System.EventHandler TestProject.TestC::MyEvent
      IL_001c: ldloc.2      // V_2
      IL_001d: ldloc.1      // V_1
      IL_001e: call         !!0/*class [mscorlib]System.EventHandler*/ [mscorlib]System.Threading.Interlocked::CompareExchange<class [mscorlib]System.EventHandler>(!!0/*class [mscorlib]System.EventHandler*/&, !!0/*class [mscorlib]System.EventHandler*/, !!0/*class [mscorlib]System.EventHandler*/)
      IL_0023: stloc.0      // V_0
      IL_0024: ldloc.0      // V_0
      IL_0025: ldloc.1      // V_1
      IL_0026: bne.un.s     IL_0007
    // end of loop
    IL_0028: ret          

  } // end of method TestC::remove_MyEvent

  .method family hidebysig instance void 
    OnMyEvent(
      class [mscorlib]System.EventArgs a
    ) cil managed 
  {
    .maxstack 8

    // [13 9 - 13 10]
    IL_0000: nop          

    // [14 13 - 14 38]
    IL_0001: ldarg.0      // this
    IL_0002: ldfld        class [mscorlib]System.EventHandler TestProject.TestC::MyEvent
    IL_0007: dup          
    IL_0008: brtrue.s     IL_000d
    IL_000a: pop          
    IL_000b: br.s         IL_0015
    IL_000d: ldarg.0      // this
    IL_000e: ldarg.1      // a
    IL_000f: callvirt     instance void [mscorlib]System.EventHandler::Invoke(object, class [mscorlib]System.EventArgs)
    IL_0014: nop          

    // [15 9 - 15 10]
    IL_0015: ret          

  } // end of method TestC::OnMyEvent

  .method public hidebysig specialname rtspecialname instance void 
    .ctor() cil managed 
  {
    .maxstack 8

    IL_0000: ldarg.0      // this
    IL_0001: call         instance void [mscorlib]System.Object::.ctor()
    IL_0006: nop          
    IL_0007: ret          

  } // end of method TestC::.ctor

  .event [mscorlib]System.EventHandler MyEvent
  {
    .addon instance void TestProject.TestC::add_MyEvent(class [mscorlib]System.EventHandler) 
    .removeon instance void TestProject.TestC::remove_MyEvent(class [mscorlib]System.EventHandler) 
  } // end of event TestC::MyEvent
} // end of class TestProject.TestC