fix: type 'Null' is not a subtype of type 'String' in getCurrentUser

[Lukitaduarte]

Instructions

1. PR target branch should be against development
2. PR title name should follow this format: https://github.com/mParticle/mparticle-workflows/blob/main/.github/workflows/pr-title-check.yml
3. PR branch prefix should follow this format: https://github.com/mParticle/mparticle-workflows/blob/main/.github/workflows/pr-branch-check-name.yml

Summary

• Currently the mParticle SDK has a null pointer bug when trying to retrieve the mpid on some Android devices.

Testing Plan

• I didn't test it locally, basically I just added a null check, an additional layer of protection to the existing check that only looks if the mpid is an empty string.

Reference Issue (For mParticle employees only. Ignore if you are an outside contributor)

• [Android] getCurrentUser Nullpointer. #45

[rmi22186]

LGTM! thanks for the PR. While we never came across this in our testing, I agree this makes the code safer.

[rmi22186]

This has been published to pub.dev as version 1.0.5 - https://pub.dev/packages/mparticle_flutter_sdk

Thanks again for your help and apologies this took a bit longer than expected to approve. I had been out for a couple weeks.

[Lukitaduarte]

@rmi22186 I appreciate it 🙏