Fix opening bytes index with dynamic codec

[PSeitz]

Fix #1278

[codecov-commenter]

Codecov Report

Merging #1279 (9c12860) into main (505e6a4) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1279      +/-   ##
==========================================
- Coverage   94.22%   94.21%   -0.02%     
==========================================
  Files         209      209              
  Lines       35294    35301       +7     
==========================================
+ Hits        33256    33259       +3     
- Misses       2038     2042       +4     

Impacted Files	Coverage Δ
src/fastfield/mod.rs	92.94% <ø> (ø)
src/fastfield/reader.rs	88.23% <ø> (-5.89%)	⬇️
src/fastfield/bytes/reader.rs	96.66% <100.00%> (ø)
src/fastfield/readers.rs	86.66% <100.00%> (ø)
src/indexer/index_writer.rs	96.92% <100.00%> (+0.01%)	⬆️
src/indexer/segment_updater.rs	94.55% <0.00%> (+0.12%)	⬆️
src/indexer/segment_manager.rs	82.55% <0.00%> (+1.34%)	⬆️

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[fulmicoton]

Please add a unit test that failed before and succeeds after @PSeitz

[fulmicoton]

unit test plz

[PSeitz]

I extended the proptest to cover that case and confirmed they fail before