Proper error handling of non-halting errors

Currently it seems to not pick up on non-halting errors, which could become an issue.
```
[GLuaTest] === Running gmod/unit/classes/file/File:ReadDouble... ===
[GLuaTest] PASS [Exists on the File meta table]
CLog::Print: string too long (>1024 bytes).L 09/17/2025 - 19:43:28: Lua Error:
[project] File:Write() - Invalid write size 0
1. Write - lua/includes/extensions/file.lua:24
2. getTestFile - addons/project/lua/gluatest/extensions/file_tools.lua:14
3. getTestFile - addons/project/lua/gluatest/extensions/file_tools.lua:52
4. unknown - lua/tests/gmod/unit/classes/file/ReadDouble.lua:18
5. xpcall - [C]:-1
6. SafeRunWithEnv - addons/gluatest/lua/gluatest/runner/helpers.lua:335
7. func - addons/gluatest/lua/gluatest/runner/test_case_runner.lua:76
8. unknown - addons/gluatest/lua/gluatest/runner/test_case_runner.lua:208
9. ProtectedCall - [C]:-1
10. cb - addons/gluatest/lua/gluatest/runner/test_group_runner.lua:136
11. func - addons/gluatest/lua/gluatest/runner/test_case_runner.lua:92
12. unknown - addons/gluatest/lua/gluatest/runner/test_case_runner.lua:208
13. ProtectedCall - [C]:-1
14. runNext - addons/gluatest/lua/gluatest/runner/test_gr
[project] File:Write() - Invalid write size 0
1. Write - lua/includes/extensions/file.lua:24
2. getTestFile - addons/project/lua/gluatest/extensions/file_tools.lua:14
3. getTestFile - addons/project/lua/gluatest/extensions/file_tools.lua:52
4. unknown - lua/tests/gmod/unit/classes/file/ReadDouble.lua:18
5. xpcall - [C]:-1
6. SafeRunWithEnv - addons/gluatest/lua/gluatest/runner/helpers.lua:335
7. func - addons/gluatest/lua/gluatest/runner/test_case_runner.lua:76
8. unknown - addons/gluatest/lua/gluatest/runner/test_case_runner.lua:208
9. ProtectedCall - [C]:-1
10. cb - addons/gluatest/lua/gluatest/runner/test_group_runner.lua:136
11. func - addons/gluatest/lua/gluatest/runner/test_case_runner.lua:92
12. unknown - addons/gluatest/lua/gluatest/runner/test_case_runner.lua:208
13. ProtectedCall - [C]:-1
14. runNext - addons/gluatest/lua/gluatest/runner/test_group_runner.lua:136
1[GLuaTest] PASS [Reads a written double correctly]
```