fix(tags): prevent metadata lookup failures from skipping group tag

Wrapped metadata provider lookup in try/except so custom tags (Group) are always applied even when IMDB/TMDB lookups fail. Also log mkvpropedit errors instead of silently discarding them.

unshackle/core/utils/tags.py

@@ -33,12 +33,15 @@ def apply_tags(path: Path, tags: dict[str, str]) -> None:
         f.write("\n".join(xml_lines))
         tmp_path = Path(f.name)
     try:
-        subprocess.run(
+        result = subprocess.run(
             [str(binaries.Mkvpropedit), str(path), "--tags", f"global:{tmp_path}"],
             check=False,
-            stdout=subprocess.DEVNULL,
-            stderr=subprocess.DEVNULL,
+            capture_output=True,
+            text=True,
         )
+        if result.returncode != 0:
+            log.warning("mkvpropedit failed (exit %d): %s", result.returncode, result.stderr.strip())
+        else:
             log.debug("Tags applied via mkvpropedit")
     finally:
         tmp_path.unlink(missing_ok=True)
@@ -92,6 +95,7 @@ def tag_file(
     standard_tags: dict[str, str] = {}
 
     if config.tag_imdb_tmdb:
+        try:
             providers = get_available_providers()
             if not providers:
                 log.debug("No metadata providers available; skipping tag lookup")
@@ -129,6 +133,8 @@ def tag_file(
 
             if result and result.external_ids:
                 standard_tags = _build_tags_from_ids(result.external_ids, kind)
+        except Exception as e:
+            log.warning("Metadata lookup failed, applying custom tags only: %s", e)
 
     apply_tags(path, {**custom_tags, **standard_tags})