fix: ensure ZipStore is open before acquiring lock

[oelhammouchi]

Fix a bug where ZipStore complains that it has no attribute _lock when some methods are called. Any method using the lock should make sure the store is opened because that's when the _lock attribute gets set.

[codecov]

Codecov Report

❌ Patch coverage is 91.66667% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 60.92%. Comparing base (b873691) to head (864e445).

Files with missing lines	Patch %	Lines
src/zarr/storage/_zip.py	91.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3593      +/-   ##
==========================================
+ Coverage   60.90%   60.92%   +0.02%     
==========================================
  Files          86       86              
  Lines       10174    10180       +6     
==========================================
+ Hits         6196     6202       +6     
  Misses       3978     3978              

Files with missing lines	Coverage Δ
src/zarr/storage/_zip.py	72.83% <91.66%> (+0.97%)	⬆️

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[d-v-b]

how did the bug you are fixing here get past the store tests? Maybe we need to make those tests stronger?

[oelhammouchi]

You're right, I didn't want to appear presumptuous but the code could do with some refactoring as well, having to repeat all those _sync_open calls in so many functions naturally increases the probability of forgetting some. Not sure if this should be done in this PR though.

[d-v-b]

if you can find a clean way to reduce the repetition (e.g., a decorator) we'd appreciate it!

[oelhammouchi]

@d-v-b just for info, I'm currently on holiday but I'm planning to implement the proposed improvements shortly

[oelhammouchi]

@d-v-b I've finally had time to revisit this! I've added tests and cleanup up the open check, the proposed decorator approach turned out not very clean imo because you'd need to test for the various types of functions (async, iterator, etc.)