How to reproduce:
1. Open user-submitted project (Unity2019.2-CustomInspectorLayoutScopeIssue)
2. Open the 'SampleScene' scene
3. Select MyObject and make sure there is a 'MyComponent' assigned script
4. Click the Test Button and keep the mouse in the Inspector window
5. (If using macOS) Click the Test Button and move the mouse to other windows/outside of the Editor

Expected result: no errors are displayed in the Console window
Actual result: multiple errors are displayed in the Console window

Reproducible with: 2019.1.0a10, 2019.1.4f1, 2019.2.0b4, 2019.3.0a4
Not reproducible with: 2017.4.27f1, 2018.4.1f1, 2019.1.0a9

Notes:
The following errors are thrown:
"Change stack is empty, did you call BeginChangeCheck first?"
"EndLayoutGroup: BeginLayoutGroup must be called first."
[macOS] The EndLayoutGroup error appears in 2018.3.0a1 - 2019.3.0a4 but doesn't appear in 2017.4.27f1