Prevent IDE error message when closing a project

Created by: vdavid

Fixes https://github.com/sourcegraph/sourcegraph/issues/36294

Had to fix the disposing hierarchy. @madppiper solved this in this PR: https://github.com/sourcegraph/sourcegraph/pull/36298, just it was in conflict with the current main so I re-created his solution in the current PR. It was also a good way to properly understand what he was doing. I think I gained a better understanding of the disposing hierarchy.

Test plan

• 47 sec Loom demoing that it works
• Check the code

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