typecheck.py: Divide by zero

[mborgerson]

   File "/root/scripts/typecheck.py", line 85, in <module>
    sys.exit(typecheck_diff(sys.argv[1], sys.argv[2]))
  File "/root/scripts/typecheck.py", line 52, in typecheck_diff
    report1 = typecheck_files(filenames)
  File "/root/scripts/typecheck.py", line 39, in typecheck_files
    report.score = (report.errors * 10 + report.warnings) / report.lines

https://github.com/angr/angr-management/actions/runs/16510225032/job/46690648143