Non matching Profiler.EndSample (BeginSample and EndSample count must match) exception and NullReferenceException is thrown when profile recorder and profile editor is enabled.

Steps To Reproduce:

1. Create new project or open attached project.
2. Open profiler window
3. Enable "Profiler Editor"
4. Enable "Record"
5. Enable "Deep profiler”
6. Enter play mode in scene
7. Exit Play Mode

Actual result:
Non matching Profiler errors and NullReferenceException are thrown on console.

Occurring on:
2018.2.0b10, 2018.2.0b7 2018.2.0b5, 2018.2.0b3, 2018.2.0a6

Working on:
2018.2.0a5, 2018.1.0f2, 2017.1.0f3

Environment:
Windows 7, 10 and Mac 10.12, 10.13

Stack Trace:
NullReferenceException: Object reference not set to an instance of an object
AddSamples.Update () (at Assets/Testcontents/AddSamples.cs:41)

Non matching Profiler.EndSample (BeginSample and EndSample count must match): EnterPlaymode

Non matching Profiler.EndSample (BeginSample and EndSample count must match): ApplicationTickTimer