`migrate unified` aborts the whole project with UnexpectedEndOfInput when a file ends in collapsed closing braces (`}}`)

[apotema]

Symptom

On CLI v1.60.1:

$ labelle migrate unified --dry-run
labelle migrate unified: failed on project '.': UnexpectedEndOfInput

No file name, no line — and the entire migration aborts on the first bad file.

Minimal repro

A project containing this single prefab (valid JSONC — python json.loads accepts it after comment stripping, and the engine loads it fine):

{
  "children": [ { "Position": { "x": 0, "y": 0 } } ],
  "components": { "rooms__Room": { "room_type": "x" } }}

→ UnexpectedEndOfInput.

The identical content with the final closers split onto their own lines parses fine:

  "components": { "rooms__Room": { "room_type": "x" } }
}

Bisect results (each variant tested in isolation): leading comments — fine; comments inside arrays — fine; newline-split ] + , — irrelevant. The trigger is exactly two or more } collapsed on the final line (}} / }}}).

Impact

flying-platform-labelle has 30 files ending this way (every hand-written room prefab), so migrate unified is unusable on the project: one cosmetic formatting habit blocks the whole engine-2.x migration path the error message of engine v2.0's rejectLegacyAliases explicitly directs users to ("Run labelle migrate unified to convert this file").

Expected

• The migrator's parser accepts anything the engine's jsonc parser accepts.
• On a parse failure, report the offending file path and continue with the remaining files instead of aborting the project.