FIX: ISXB-1208 fix InvalidOperationException when entering playmode

[smnwttbr]

Description

When entering playmode with domain reload disabled, an InvalidOperationException is thrown.

ISXB-1208

Testing status & QA

Package test run ok. This work builds on fixes for https://jira.unity3d.com/browse/ISX-1902, it would be worth checking this case is still resolved with these changes.

Overall Product Risks

• Complexity: 0
• Halo Effect: 0

Comments to reviewers

Please describe any additional information such as what to focus on, or historical info for the reviewers.

Checklist

Before review:

• Changelog entry added.
  • Explains the change in Changed, Fixed, Added sections.
  • For API change contains an example snippet and/or migration example.
  • JIRA ticket linked, example (case %%). If it is a private issue, just add the case ID without a link.
  • Jira port for the next release set as "Resolved".
• Tests added/changed, if applicable.
  • Functional tests Area_CanDoX, Area_CanDoX_EvenIfYIsTheCase, Area_WhenIDoX_AndYHappens_ThisIsTheResult.
  • Performance tests.
  • Integration tests.
• Docs for new/changed API's.
  • Xmldoc cross references are set correctly.
  • Added explanation how the API works.
  • Usage code examples added.
  • The manual is updated, if needed.

During merge:

• Commit message for squash-merge is prefixed with one of the list:
  • NEW: ___.
  • FIX: ___.
  • DOCS: ___.
  • CHANGE: ___.
  • RELEASE: 1.1.0-preview.3.

After merge:

• Create forward/backward port if needed. If you are blocked from creating a forward port now please add a task to ISX-1444.

[ekcoh]

Change makes sense to me and is small. If this resolves the issue it's great. Would recommend looking for potential side effects in testing, e.g. when disabling/enabling the UI component outside of domain reload scenario.