[v4 GUI] TypeError: Cannot read properties of undefined (reading 'toLowerCase') crashes app immediately after loading almost any folder or session

[wonnami]

This report concerns the v4 GUI application ("Docs par Archifiltre"), not the new v5 CLI tool in this repository.

Environment

OS	Architecture	App Version	Result
macOS (M1 Max)	arm64	v4.2.1	Crash
macOS (M1 Max)	x64 (Rosetta)	v4.2.1	Crash
macOS (M1 Max)	arm64	v4.1.2	Crash
macOS (M1 Max)	x64 (Rosetta)	v4.1.2	Crash
macOS (M2)	—	v4.2.1	Crash
Windows 11	—	v4.2.1	Crash

Description

The app crashes to a generic "Something went wrong." error screen almost immediately after a folder scan or session load completes (sometimes after the audit report generation succeeds, sometimes with no user interaction at all). Reproduced across multiple machines, app versions, and CPU architectures.

Error message
TypeError: Cannot read properties of undefined (reading 'toLowerCase')

Likely source location

Based on reviewing the v4.2.1 source, this matches getFileTypeFromFileName in src/renderer/utils/file-types.ts:

const extName = path.extname(fileName.toLowerCase()); // fileName appears to be undefined here

Called automatically after loading from:

• src/renderer/exporters/audit/audit-report-values-computer.ts
• src/renderer/utils/duplicates.ts
• src/renderer/utils/color.ts

Steps to reproduce

1. Scan any folder (tested with genuine source data and minimal single-file test folders — folder content does not appear to matter)
2. Wait for loading / audit report generation to complete
3. App crashes, either automatically or after clicking the "Audit report is ready" notification

What we ruled out

• App version (v4.1.2, v4.2.1)
• CPU architecture (arm64, x64/Rosetta)
• OS (macOS, Windows 11)
• Folder content (single genuine file, empty test folder)
• Full Disk Access / permissions on macOS
• Clean reinstall (removing Application Support, Preferences, Caches)

Attached
Session JSON captured just before a crash, showing a well-formed filesAndFolders structure with no missing name fields.

crash-session-example.json

[wonnami]

Additional findings after filing:

1. The type column in the Excel/CSV export is "unknown" for ALL
   entries — .sqlite, .plist, .lock, and extensionless files alike.
   This supports getFileTypeFromFileName as the failure point.

2. The progress bars stopping at 99.79% appear to be an off-by-one
   display issue rather than a data failure: 476/477 = 99.79%, and
   the exported JSON contains all 477 entries with MD5 hashes, no
   missing fields.

3. The crash also occurs with networking disabled, so it is not
   related to the current archifiltre.org outage (502). Note:
   timing to crash varies between runs, and I have not been able
   to identify a consistent trigger.

4. In one run the export completed before the crash, producing a
   complete and valid file. I cannot confirm whether this is
   reproducible.