Write UT for ChatE2EE class

[muke1908]

ChatE2EE class should be covered by Unit Test

https://github.com/muke1908/chat-e2ee/blob/master/service/src/sdk.ts

[rohan-naik07]

Will start with this one first...as it will deepen my understanding

[muke1908]

@rohan-naik07 thanks but I believe it's possible to work on #289 without an understanding of internals. The SDK is supposed to usable by anyone without knowing how code works internally. Feel free to suggest if the readme lacks any info.