refactor: clean up conversion and crossterm errors

[ClementTsang]

Description

A description of the change, what it does, and why it was made. If relevant (such as any change that modifies the UI), please provide screenshots of the changes:

This knocks out CrosstermError (which wasn't used) and ConversionError.

Issue

If applicable, what issue does this address?

Closes: #

Testing

If relevant, please state how this was tested. All changes must be tested to work:

If this is a code change, please also indicate which platforms were tested:

• Windows
• macOS
• Linux

Checklist

If relevant, ensure the following have been met:

• Areas your change affects have been linted using rustfmt (cargo fmt)
• The change has been tested and doesn't appear to cause any unintended breakage
• Documentation has been added/updated if needed (README.md, help menu, doc pages, etc.)
• The pull request passes the provided CI pipeline
• There are no merge conflicts
• If relevant, new tests were added (don't worry too much about coverage)

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 4 lines in your changes missing coverage. Please review.

Project coverage is 40.84%. Comparing base (571a801) to head (098986b).

Files	Patch %	Lines
src/data_collection/processes/unix/user_table.rs	0.00%	3 Missing ⚠️
src/data_collection/temperature/linux.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1493      +/-   ##
==========================================
+ Coverage   40.82%   40.84%   +0.02%     
==========================================
  Files         102      102              
  Lines       17632    17622      -10     
==========================================
  Hits         7198     7198              
+ Misses      10434    10424      -10     

Flag	Coverage Δ
macos-12	36.22% <0.00%> (+0.01%)	⬆️
ubuntu-latest	42.79% <0.00%> (+0.02%)	⬆️
windows-2019	36.36% <ø> (+0.01%)	⬆️

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