How to reproduce:
1. Open attached Unity project "New Unity Project"
2. Load scene "s"
3. Enter Play mode
4. Select GameObject
5. In the inspector Change Size of the Array

Expected result: New element appears in the array without any errors.
Actual result: New element appears in the array along with two errors for each element: "GetBool is not allowed to be called during serialization, call it from Awake or Start instead".

Reproducible with: 2018.1.0a3, 2017.3.0b9, 2017.2.0p2.
Not reproducible with: 2017.1.2p2, 5.6.4p2, 5.5.5p1.

Note: resizing array via script cause not errors.