Handle the case of the java version is undefined correctly

[nils-braun]

No description provided.

[codecov-io]

Codecov Report

Merging #101 (9894a54) into main (f98b0b2) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##              main      #101   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           35        35           
  Lines         1461      1460    -1     
  Branches       201       201           
=========================================
- Hits          1461      1460    -1     

Impacted Files	Coverage Δ
dask_sql/utils.py	100.00% <ø> (ø)

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