(android) Defensive code to prevent NULL reference exceptions for async

[alexyazvinsky]

Platforms affected

Android

Motivation and Context

Defensive code to prevent NULL reference exceptions for async

Description

Testing

Checklist

• I've run the tests to see all new and existing tests pass
• I added automated test coverage as appropriate for this change
• Commit is prefixed with (platform) if this change only applies to one platform (e.g. (android))
• If this Pull Request resolves an issue, I linked to the issue in the text above (and used the correct keyword to close issues using keywords)
• I've updated the documentation if necessary

[NiklasMerz]

I like to live dangerous and rebased this PR and did the suggested changes. I hope I did not mess anything up. A backup is in my fork here

That's what I did:

• rebased the PR to latest master
• did an interactive rebase to squash the two relevant commits and drop the reverted changes
• changed the author to @alexyazvinsky and pushed this as a signed commit since I did this
• Did the suggested changes separately

I hope that makes this PR better to read and follows the Apache guidelines. We should merge this and not squash merge to make the authors and history clear.

[NiklasMerz]

LGTM now 👍