fix: name a missing database in one error line

scripts/common.py

@@ -31,10 +31,30 @@ except ImportError:
 
 
 
+class DatabaseUnreadable(FileNotFoundError):
+    """The database a command was pointed at does not exist or is not JSON."""
+
+
 def load_database(db_path: str) -> dict:
-    """Load database.json and return parsed dict."""
-    with open(db_path) as f:
-        return json.load(f)
+    """Load database.json and return parsed dict.
+
+    A missing or damaged file raises DatabaseUnreadable, which run_cli turns
+    into one line saying how to build it: `--db nosuch.json` ended at the
+    bottom of a stack trace.
+    """
+    try:
+        with open(db_path) as f:
+            return json.load(f)
+    except FileNotFoundError:
+        raise DatabaseUnreadable(
+            f"{db_path} not found. Build it with: python scripts/generate_db.py "
+            "--force --bios-dir bios --output database.json"
+        ) from None
+    except json.JSONDecodeError as exc:
+        raise DatabaseUnreadable(
+            f"{db_path} is not valid JSON ({exc}). Rebuild it with: "
+            "python scripts/generate_db.py --force --bios-dir bios --output database.json"
+        ) from None
 
 
 
@@ -2501,6 +2521,9 @@ def run_cli(main: Callable[[], int | None]) -> None:
     try:
         code = main()
         sys.stdout.flush()
+    except DatabaseUnreadable as exc:
+        print(f"ERROR: {exc}", file=sys.stderr)
+        sys.exit(1)
     except BrokenPipeError:
         os.dup2(os.open(os.devnull, os.O_WRONLY), sys.stdout.fileno())
         sys.exit(141)

scripts/generate_pack.py

@@ -2426,8 +2426,7 @@ def _run_verify_packs(args: argparse.Namespace) -> None:
     second implementation here answered a narrower one and reported OK while
     the core extras went unchecked.
     """
-    with open(args.db) as f:
-        verify_db = json.load(f)
+    verify_db = load_database(args.db)
 
     if args.platform:
         platforms = [args.platform]

scripts/generate_truth.py

@@ -78,8 +78,9 @@ def main(argv: list[str] | None = None) -> None:
     profiles = load_emulator_profiles(args.emulators_dir)
 
     # Load database (optional)
+    # The default may be absent; a --db that was named must exist.
     db: dict | None = None
-    if os.path.exists(args.db):
+    if args.db != DEFAULT_DB_FILE or os.path.exists(args.db):
         db = load_database(args.db)
 
     # Determine platforms

scripts/slots.py

@@ -807,6 +807,7 @@ def main() -> int:
 
     from common import (
         list_registered_platforms,
+        load_database,
         load_emulator_profiles,
         load_platform_config,
         require_platform,
@@ -830,8 +831,7 @@ def main() -> int:
     )
     args = parser.parse_args()
 
-    with open(args.db, encoding="utf-8") as handle:
-        db = json.load(handle)
+    db = load_database(args.db)
     profiles = load_emulator_profiles(args.emulators_dir)
     if args.platform:
         require_platform(args.platform, args.platforms_dir)

scripts/validate_pr.py

@@ -326,13 +326,15 @@ def _files_to_validate(
 
 
 def _load_database_if_any(path: str) -> dict | None:
-    try:
-        return load_database(path)
-    except FileNotFoundError:
-        return None
-    except json.JSONDecodeError as e:
-        print(f"WARNING: corrupt database.json: {e}", file=sys.stderr)
+    """The database, optional only where the default is meant.
+
+    A mistyped --db read as "no database" and every file passed its
+    duplicate and placement checks unchecked; a damaged one did the same
+    after a warning.
+    """
+    if path == DEFAULT_DB and not os.path.exists(path):
         return None
+    return load_database(path)
 
 
 def main() -> None:

scripts/verify.py

@@ -56,6 +56,7 @@ from common import (
     list_emulator_profiles,
     list_system_ids,
     load_data_dir_registry,
+    load_database,
     load_emulator_profiles,
     load_platform_config,
     md5sum,
@@ -2178,8 +2179,7 @@ def _main(held: contextlib.ExitStack) -> None:
 
     hold_data_dirs(held, load_data_dir_registry(args.platforms_dir))
 
-    with open(args.db) as f:
-        db = json.load(f)
+    db = load_database(args.db)
 
     # Emulator mode
     if args.emulator: