Enable Typescript strict mode

[notmd]

We need to enable Typescript strict mode to make out code safe. This needs to be incremental cause we don't want to break the build.

• Set TS strict option to true in the tsconfig file.
• Going through each file and checking if there is any error need to fix (or run npm run typecheck).

We should make small PRs to easily review and avoid conflict.

[KarthikRaju391]

@fozziethebeat, I would like to work on this!

[EpicLiem]

I'll do a few files