Description of changes:
Code does not check whether observer is null or undefined which sometimes happen.
I added a check similar to the checks being done earlier in the same function.
By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.
Issue #, if available: https://github.com/awslabs/aws-mobile-appsync-sdk-js/issues/688
Description of changes: Code does not check whether observer is null or undefined which sometimes happen. I added a check similar to the checks being done earlier in the same function.
By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.