fix: show clean error message when MusicBrainz barcode lookup fails

Catch ValueError (barcode not found) and httpx.HTTPError (network error)
in _scan_to_album and print a user-friendly message with hint instead of
a raw Python traceback. Also remove unused `call` import in test_ripper.py.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/musiksammlung/cli.py

@@ -6,6 +6,7 @@ import json
 import logging
 from pathlib import Path
 
+import httpx
 import typer
 from mutagen import File as MutagenFile
 
@@ -46,7 +47,18 @@ def _scan_to_album(
     """Gemeinsame Scan-Logik: Barcode, Text-Datei, Vision-LLM oder OCR+LLM."""
     if barcode:
         typer.echo(f"MusicBrainz-Suche nach Barcode {barcode}...")
-        return lookup_by_barcode(barcode)
+        try:
+            return lookup_by_barcode(barcode)
+        except ValueError as e:
+            typer.echo(f"Fehler: {e}", err=True)
+            typer.echo(
+                "Tipp: Barcode prüfen oder Metadaten per --from-text / --vision ermitteln.",
+                err=True,
+            )
+            raise typer.Exit(1)
+        except httpx.HTTPError as e:
+            typer.echo(f"Netzwerkfehler bei MusicBrainz-Abfrage: {e}", err=True)
+            raise typer.Exit(1)
     elif from_text:
         text = from_text.read_text(encoding="utf-8")
         typer.echo(f"Text-Datei geladen ({len(text)} Zeichen). LLM-Parsing...")

tests/test_ripper.py

@@ -1,7 +1,7 @@
 """Tests für den CD-Ripper."""
 
 from pathlib import Path
-from unittest.mock import MagicMock, call, patch
+from unittest.mock import MagicMock, patch
 
 from musiksammlung.config import AudioFormat
 from musiksammlung.models import Album, Disc, Track