Suppress 404 error for notebook route when the notebook is not running

[DaoDaoNoCode]

Description

Closes #858

How Has This Been Tested?

There is no good way to test it because once you delete the route, it will recreate one immediately before re-fetching it. I tested it by changing the notebookName to something else, which will give you a 404 error when you are trying to get the route, but the isRunning status is always accurate. In this way, I can toggle the switch and see if the error is set or not when based on the notebook status.

Merge criteria:

• The commits are squashed in a cohesive manner and have meaningful messages.
• Testing instructions have been added in the PR body (for PRs involving changes that are not immediately obvious).
• The developer has manually tested the changes and verified that the changes work

[Gkrumbach07]

I created a way to force a 404 error. In the old implementation, 404 would persist even while loading. In the new implementation there is no error until loaded.

I had concerns about setting error to null everytime being unnessary

if (!isRunning && e.statusObject?.code === 404) {
    setLoadError(null);
}

But in the case where there was an error while running, and the user stops and starts again, the error wont go away until a successful call is made. So no issue there. unless it would be desired to keep the error after it has been shut down (doubt it is so lgtm).

/lgtm

[lucferbux]

/lgtm

[andrewballantyne]

Should help with the optics of what is going on during the load. Either way, when the route eventually comes back it should reset to being active (previous functionality). Good improvement for the meantime.

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: andrewballantyne, Gkrumbach07, lucferbux

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