fix: add type checks in linting script [WD-13573]

[mas-who]

Done

• Added type checks to the lint-js script. This should pick up typescript errors that previously was missed during CI.
• Fixed some Typescript errors that existed in the codebase

QA

1. Run the LXD-UI:
   • On the demo server via the link posted by @webteam-app below. This is only available for PRs created by collaborators of the repo. Ask @mas-who or @edlerd for access.
   • With a local copy of this branch, build and run as described in the docs.
2. Perform the following QA steps:
   • N/A

[webteam-app]

Demo

Jenkins

demos.haus

[Kxiru]

Thanks for addressing these changes!