"Requested frame does not exists" exception thrown on clearing UI frame data.

Steps to repro:
1. Create a new project.
2. Windows > Analysis > Profiler.
3. Add UI Profiler.
4. Select frame in UI section.
5. Clear the Profiler data.

Actual Result:
Exceptions are thrown in the console.

Expected Result:
Profiler data should be clear without exceptions.

Reproducible with:
2019.3.0a5, 2019.2.0b5.

Working Fine with:
2018.2.0a5.

Environment:
Windows & Mac

Stacktrace:
Requested frame does not exists
UnityEditorInternal.ProfilerProperty:SetRoot(Int32, Int32, Int32)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)