[BUG] Addon panel is rendered on top of other addon panels

[yannbf]

Hey there! it seems like one of the error states of the panel is getting rendered on top of other panels.

To reproduce, just access any "No Story Source" story

[dongyunlee-daim]

We've just resolved this issue.

However, the "UseStoryPrepared" hook I use to check if a story is ready is having issues.
so I had to create a separate code utilizing the sb api. I created a PR that fixes the "useStoryPrepared" hook, but it keeps failing the lint test, so this is a workaround for the time being. Once I fix the issues with the useStoryPrepared hook, I'll fix the code in a cleaner way.

Fwiw) PR link : storybookjs/storybook#22631