fix: better error for concurrent create

[wjones127]

Fixes #2403

[wjones127]

Follow up issue here: #2961

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 88.37209% with 5 lines in your changes missing coverage. Please review.

Project coverage is 79.00%. Comparing base (396b4d1) to head (1302ffd).
Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
rust/lance/src/dataset.rs	88.23%	0 Missing and 4 partials ⚠️
rust/lance/src/io/commit.rs	88.88%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2962      +/-   ##
==========================================
+ Coverage   78.99%   79.00%   +0.01%     
==========================================
  Files         234      234              
  Lines       72829    72894      +65     
  Branches    72829    72894      +65     
==========================================
+ Hits        57530    57589      +59     
- Misses      12329    12333       +4     
- Partials     2970     2972       +2     

Flag	Coverage Δ
unittests	79.00% <88.37%> (+0.01%)	⬆️

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