Better error messages on database loading errors.

paskia/__main__.py

@@ -1,11 +1,13 @@
 import argparse
 import logging
 import os
+import sys
 
 import msgspec
 from fastapi_vue import server
 from fastapi_vue.hostutil import parse_endpoints
 
+from paskia._version import __version__
 from paskia.db.jsonl import load_readonly
 from paskia.util import startupbox
 from paskia.util.hostutil import (
@@ -74,7 +76,11 @@ def main():
 
     # Load stored config (read-only, no writes, no global state)
     db_path = os.environ.get("PASKIA_DB", f"{args.rp_id}.paskiadb")
-    config = load_readonly(db_path, rp_id=args.rp_id).config
+    try:
+        config = load_readonly(db_path, rp_id=args.rp_id).config
+    except SystemExit as e:
+        print(f"🛑 Paskia {__version__} could not load")
+        sys.exit(str(e))
 
     # Override stored config with CLI args, or clear with empty string
     if args.rp_name is not None:

paskia/db/jsonl.py

@@ -41,11 +41,9 @@ class ReplayResult(msgspec.Struct, frozen=False):
     changes: int = 0
 
 
-class DatabaseError(Exception):
+class DatabaseError(ValueError):
     """Exception raised for database loading errors."""
 
-    pass
-
 
 def _replay_from_data(data: bytes, db_path: str) -> ReplayResult:
     """Replay database state from file data, using the last snapshot if available."""
@@ -61,14 +59,16 @@ def _replay_from_data(data: bytes, db_path: str) -> ReplayResult:
 
     # Replay change records after the snapshot
     lines = data[start_offset:].split(b"\n")
-    for line_num, raw in enumerate(lines, start=1):  # 1-based line numbering
+    for raw in lines:
         line = raw.strip()
         if not line:
             continue
         try:
             change = msgspec.json.decode(line, type=ChangeRecord)
         except msgspec.DecodeError as e:
-            raise DatabaseError(f"{resolved_path}:{line_num}: {e}")
+            raise DatabaseError(
+                f"{resolved_path}: {e}\n{line.decode(errors='replace')}"
+            )
         result.state = jsondiff.patch(result.state, change.diff, marshal=True)
         result.v = change.v
         result.ts = change.ts
@@ -88,30 +88,31 @@ def load_readonly(db_path: str, *, rp_id: str = "localhost") -> DB:
         return DB(config=Config(rp_id=rp_id))
 
     try:
-        with open(path, "rb") as f:
-            content = f.read()
+        content = path.read_bytes()
         r = _replay_from_data(content, str(path.resolve()))
         data_dict = r.state
         version = r.v
+
+        if not data_dict:
+            return DB(config=Config(rp_id=rp_id))
+
+        # Apply migrations in-memory (no persistence)
+        apply_migrations_readonly(data_dict, version, MigrationCtx(rp_id=rp_id))
+
+        # Decode to msgspec struct
+        try:
+            return msgspec.json.decode(msgspec.json.encode(data_dict), type=DB)
+        except msgspec.ValidationError as e:
+            raise DatabaseError(f"{path.resolve()}: {e}") from None
     except OSError as e:
         _logger.exception("Failed to load database")
         raise SystemExit(f"{e}")
-    except (ValueError, msgspec.DecodeError, DatabaseError) as e:
+    except (ValueError, msgspec.DecodeError) as e:
         raise SystemExit(f"{e}")
     except Exception as e:
         _logger.exception("Unexpected error loading database")
         raise SystemExit(f"{e}")
 
-    if not data_dict:
-        return DB(config=Config(rp_id=rp_id))
-
-    # Apply migrations in-memory (no persistence)
-    apply_migrations_readonly(data_dict, version, MigrationCtx(rp_id=rp_id))
-
-    # Decode to msgspec struct
-    db = msgspec.json.decode(msgspec.json.encode(data_dict), type=DB)
-    return db
-
 
 class ChangeRecord(msgspec.Struct, omit_defaults=True, kw_only=True):
     ts: datetime = msgspec.field(default_factory=lambda: datetime.now(UTC))