sed: keep script position for errors at end of script

[sylvestre]

An error found once the script is exhausted, like an unterminated command, lost its location and was reported as :0:N. Keep the last input name and line number, so it points at the script argument or file line, as GNU sed does.

$ sed --posix 'i\'
before: sed: :0:3: error: incomplete command
after:  sed: <script argument 1>:1:3: error: incomplete command
GNU:    sed: -e expression #1, char 2: incomplete command

$ sed 's/a/b\'
before: sed: :0:7: error: unterminated substitute replacement (unexpected EOF)
after:  sed: <script argument 1>:1:7: error: unterminated substitute replacement (unexpected EOF)
GNU:    sed: -e expression #1, char 6: unterminated `s' command

Split out of #576.

[Copilot]

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[codecov]

Codecov Report

❌ Patch coverage is 61.53846% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.83%. Comparing base (72ed709) to head (43681a9).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
src/sed/script_line_provider.rs	61.53%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #579      +/-   ##
==========================================
- Coverage   83.87%   83.83%   -0.05%     
==========================================
  Files          14       14              
  Lines        6977     6984       +7     
  Branches      407      407              
==========================================
+ Hits         5852     5855       +3     
- Misses       1121     1125       +4     
  Partials        4        4              

Flag	Coverage Δ
macos_latest	84.98% <61.53%> (-0.05%)	⬇️
ubuntu_latest	85.18% <61.53%> (-0.05%)	⬇️
windows_latest	0.00% <0.00%> (ø)

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[github-actions]

GNU sed testsuite comparison:

Test results comparison:
  Current:   TOTAL: 65 / PASSED: 15 / FAILED: 42 / SKIPPED: 8
  Reference: TOTAL: 65 / PASSED: 14 / FAILED: 43 / SKIPPED: 8

Changes from main branch:
  TOTAL: +0
  PASSED: +1
  FAILED: -1

Test improvements (1):
  + cmd-R

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[codspeed]

Merging this PR will degrade performance by 5.26%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 1 improved benchmark
❌ 1 regressed benchmark
✅ 9 untouched benchmarks

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
❌	number_fix	1.1 s	1.3 s	-13.81%
⚡	access_log_subst	2.4 s	2.3 s	+4.13%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing sylvestre:script-end-position (43681a9) with main (72ed709)}