Fix FromBytes::read_from_suffix return type; remove panic paths

[jswrenn]

FromBytes::read_from_suffix should return a SizeError, like read_from_bytes and read_from_prefix. This commit corrects this error, and also removes unreachable panic paths in all three functions.

Makes progress towards #1692

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 77.77778% with 2 lines in your changes missing coverage. Please review.

Project coverage is 88.61%. Comparing base (42ce158) to head (2d5304d).
Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
src/lib.rs	77.77%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1716      +/-   ##
==========================================
- Coverage   88.98%   88.61%   -0.38%     
==========================================
  Files          16       16              
  Lines        5830     5858      +28     
==========================================
+ Hits         5188     5191       +3     
- Misses        642      667      +25     

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