Handle errors in auto-tracing better

[alexmojaki]

1. When a file has invalid syntax, skip auto-tracing so that it can be imported normally and produce a normal traceback.
2. Handle internal errors when modifying and compiling the AST so that the app still works and just logs an error about auto-tracing failing.

For both of these, compiling had to be moved from the import loader to the import finder.

[cloudflare-workers-and-pages]

Deploying logfire-docs with    Cloudflare Pages

Latest commit:	2d3276c
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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (b9f37ee) to head (2d3276c).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #610   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          133       133           
  Lines        10556     10561    +5     
  Branches      1450      1450           
=========================================
+ Hits         10556     10561    +5     

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[davidhewitt]

Looks like good improvements to me 👍