Make isosurfaces more robust

[philippotto]

• don't crash front-end if isosurface request fails
• retry isosurface requests if they fail
• indicate loading state of isosurfaces also on initial request

URL of deployed dev instance (used for testing):

• https://robustisosurfaces.webknossos.xyz

Steps to test:

• open a dataset with segmentation
• set network speed to slow
• request an isosurface --> a loading icon should be visible as long as the request is pending
• set network setting to offline
• request an isosurface --> a loading icon should appear and the console should log details about retries
• set network setting to online --> the isosurface generation should succeed on the next retry

Issues:

• follow up Failing isosurface requests crash front-end #5101

---

• Updated (unreleased) changelog
• Updated (unreleased) migration guide if applicable
• Updated documentation if applicable
• Adapted wk-connect if datastore API changes
• Needs datastore update after deployment
• Ready for review

[philippotto]

@grittaweisheit do you know why addIsosurfaceAction is only dispatched if there is a seedPosition ? 1) The used position is set to the current annotation position and used as a seed if seedPosition == null, so it should be fine to use that here, too? 2) I'm not really sure in which cases seedPosition is null anyway. The signature states seedPosition: ?Vector, but all callers seem to pass it if I'm not missing anything?

[grittaweisheit]

I think it is because ensureSuitableIsosurface is also called at every flycam movement, but we don't really want to add an isosurface then. And since there is no seed position in that case, that is the way I decided whether to dispatch the addIsosurfaceAction or not.

[philippotto]

Ok, makes sense. Good point with the flycam-movement listener! I missed that. However, the "if seed position is null, we know it was caused by a flycam movement"-logic is a bit too hidden for me. I just changed the code to simply dispatch addIsosurfaceAction everytime unless it already exists in the store. This is bit more intuitive and safer in my opinion.

[daniel-wer]

Very nice, LGTM once your question was answered 👍