fix(bundler): degrade non-UTF-8 config reads into BundlerError

[jawwad-ali]

Problem

bundler/lib/yamlio.py is the single chokepoint for every bundler read, and its module docstring states the contract explicitly:

All reads/writes go through these functions so that IO failures degrade into actionable BundlerErrors rather than raw tracebacks.

Both readers catch only OSError. But Path.read_text(encoding="utf-8") and json.load() raise UnicodeDecodeError on a non-UTF-8 file, and:

issubclass(UnicodeDecodeError, OSError)  # False   (MRO: UnicodeError -> ValueError)

So the decode error escapes uncaught. Reproduced on main with a UTF-16 file:

load_yaml: LEAKED UnicodeDecodeError -> 'utf-8' codec can't decode byte 0xff in position 0
load_json: LEAKED UnicodeDecodeError -> 'utf-8' codec can't decode byte 0xff in position 0

In load_json, json.JSONDecodeError does not cover it — the two are sibling ValueError subclasses, neither subsumes the other.

This is realistic rather than theoretical: on Windows, PowerShell 5.1's Out-File and > default to UTF-16, so a hand-edited .specify/bundle-catalogs.yml or records file lands here.

Fix

Widen both read clauses to (OSError, UnicodeError) — matching the sibling catalog readers (catalogs.py:101, workflows/catalog.py:336, which already use exactly this tuple).

json.JSONDecodeError deliberately stays first in load_json, so malformed-but-decodable JSON keeps its more specific Invalid JSON message while a decode failure falls through to the read-error clause. A regression test locks that ordering.

Scope: reads only. I verified the write paths do not leak UnicodeEncodeError — dump_yaml/dump_json both escape unencodable input (tested with a lone surrogate), so there is nothing to fix there.

Verification

• test_load_yaml_non_utf8_raises_bundler_error and test_load_json_non_utf8_raises_bundler_error (UTF-16 input): fail before with the raw UnicodeDecodeError, pass after.
• test_load_json_malformed_still_reports_invalid_json: clause-order guard — decodable-but-malformed JSON still reports Invalid JSON.
• tests/unit/test_bundler_yamlio.py: 5 passed.
• tests/unit/ + tests/contract/: 252 passed (2 pre-existing Windows symlink-privilege failures, unrelated — they need admin and pass on CI's Linux/macOS runners).
• uvx ruff@0.15.0 check src tests clean.

No behaviour change for UTF-8 input: those reads take the identical path and return identical values.

---

AI-assisted: authored with Claude Code. I reproduced both leaks on main, checked issubclass rather than assuming, verified the write paths were safe before scoping the fix, and matched the existing sibling-reader tuple.