*: check if GetStore returns nil (#4347)

[ti-chi-bot]

This is an automated cherry-pick of #4347

close #4344

Signed-off-by: disksing i@disksing.com

What problem does this PR solve?

If we use remove tombstone, GetStore may return nil. We should check it.

What is changed and how it works?

Check List

Tests

• Unit test

Related changes

• Need to cherry-pick to the release branch

Release note

Fix panic issue after TiKV node scales in

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• JmPotato
• lhy1024

To complete the pull request process, please ask the reviewers in the list to review by filling /cc @reviewer in the comment.
After your PR has acquired the required number of LGTMs, you can assign this pull request to the committer in the list by filling /assign @committer in the comment to help you merge this pull request.

The full list of commands accepted by this bot can be found here.

Reviewer can indicate their review by submitting an approval review.
Reviewer can cancel approval by submitting a request changes review.

[nolouch]

test failed.

[disksing]

/run-all-tests

[ti-chi-bot]

[FORMAT CHECKER NOTIFICATION]

Please provide the associated issue number in the commit messages, for example: close #12345, or ref #12345.

[codecov]

Codecov Report

Merging #4378 (730c3bf) into release-4.0 (b2c3de6) will decrease coverage by 0.35%.
The diff coverage is 27.27%.

@@               Coverage Diff               @@
##           release-4.0    #4378      +/-   ##
===============================================
- Coverage        75.31%   74.96%   -0.36%     
===============================================
  Files              211      211              
  Lines            20081    20090       +9     
===============================================
- Hits             15125    15061      -64     
- Misses            3620     3695      +75     
+ Partials          1336     1334       -2     

Flag	Coverage Δ
unittests	74.96% <27.27%> (-0.36%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
server/schedule/region_scatterer.go	74.23% <0.00%> (-2.00%)	⬇️
server/schedulers/shuffle_region.go	77.21% <50.00%> (-1.74%)	⬇️
server/statistics/store.go	76.88% <100.00%> (ø)
server/statistics/store_collection.go	58.53% <0.00%> (-34.96%)	⬇️
server/region_syncer/server.go	79.41% <0.00%> (-9.56%)	⬇️
pkg/dashboard/adapter/manager.go	80.85% <0.00%> (-4.26%)	⬇️
server/cluster/cluster.go	76.89% <0.00%> (-3.29%)	⬇️
pkg/btree/btree.go	85.30% <0.00%> (-0.97%)	⬇️
server/cluster/coordinator.go	68.43% <0.00%> (-0.80%)	⬇️
server/schedule/operator_controller.go	81.01% <0.00%> (-0.59%)	⬇️
... and 8 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b2c3de6...730c3bf. Read the comment docs.

[JmPotato]

/merge

[ti-chi-bot]

@JmPotato: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 730c3bf