Never skip a local index error for a directory or symlink (closes #284)

Under --skip-errors, an error recording a directory or symlink in the
local index was skipped like an unreadable file. The snapshot completed
without the entry, and a restore did not recreate it.

processFileWithErrorHandling now records a directory or symlink itself
and returns any error, which stops the backup with or without the flag.
The skip sees only a regular file's errors.

The test injects the error with a SQLite trigger that refuses the
directory's files row.

Model: opus-5-5

TODO.md

@@ -22,6 +22,15 @@ the tag exists and is exercised; what is left is merging `next` to
 
 # Completed Steps
 
+- 2026-10-08: Made a local index error while recording a directory or
+  symlink stop a backup under `--skip-errors`
+  ([issue #284](https://git.eeqj.de/sneak/vaultik/issues/284)). Phase 2
+  only records such an entry in the local index, since it has no data
+  to open or read, but an error doing so was skipped like an unreadable
+  file. The snapshot then completed without the entry, and a restore
+  did not recreate it. The error now stops the backup, as it does
+  without the flag.
+
 - 2026-10-08: Counted a file that a backup could not store as failed
   ([issue #280](https://git.eeqj.de/sneak/vaultik/issues/280)). A file
   that phase 1 counted and phase 2 could not open, because it was