fix(ui/blocks): fixing overlapping blocks for undefined poolArrays

[outofrange]

It appears that poolArray[0][0] can return undefined, resulting in an error when trying to read .thanos.

I haven't dug deeper into why it's undefined, so there is a root cause that should be fixed instead?

• I added CHANGELOG entry for this change.

Fixes #7216

Changes

Using ?. to catch undefined poolArrays.

Verification

If have only tested this with my Thanos deployment, which hasn't any overlapping blocks - can someone check if this works also when there are overlapping blocks present?

[outofrange]

An E2E test is failing:

15:27:12 toolsBucketWeb-1: ts=2024-03-28T15:27:12.979772333Z caller=runutil.go:117 level=error name=toolsBucketWeb-1 msg="function failed. Retrying in next tick" err="BaseFetcher: iter bucket: Get \"https://127.0.0.1:32790/toolsBucketWeb-test/?location=\": dial tcp 127.0.0.1:32790: connect: connection refused"
15:27:21 toolsBucketWeb-1: ts=2024-03-28T15:27:21.698806328Z caller=runutil.go:117 level=error name=toolsBucketWeb-1 msg="function failed. Retrying in next tick" err="BaseFetcher: iter bucket: Get \"https://127.0.0.1:32805/toolsBucketWeb-test/?location=\": dial tcp 127.0.0.1:32805: connect: connection refused"
panic: test timed out after 10m0s

Don't see why my change would cause a connection refused, but toolsBucketWeb at least looks like it could be related - or is this a flake?

[yeya24]

I believe it is a flake. Just re ran the test

[GiedriusS]

Maybe you could try copying the tests from #7058 to see whether they pass?