log error when failed to read POS data from file

[poszu]

Added an error log message that will print:

• the path of the file that it failed to read from,
• the position in this file
• the total size of the file
• the actual error

Previously, the error was swallowed without notifying the user something was wrong.

[codecov]

Codecov Report

Attention: Patch coverage is 73.33333% with 4 lines in your changes missing coverage. Please review.

Project coverage is 93.03%. Comparing base (8bd1370) to head (51cf87c).

Files with missing lines	Patch %	Lines
src/reader.rs	73.33%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #517      +/-   ##
==========================================
- Coverage   93.09%   93.03%   -0.07%     
==========================================
  Files          29       29              
  Lines        3621     3632      +11     
==========================================
+ Hits         3371     3379       +8     
- Misses        250      253       +3     

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