catch config errors in run command instead of crashing

src/hookrelay/cli.py

@@ -25,7 +25,11 @@ def _read_data(spec: str | None) -> str:
 
 
 def cmd_run(args: argparse.Namespace) -> int:
-    config = load_config(args.config)
+    try:
+        config = load_config(args.config)
+    except ConfigError as e:
+        print(f"config error: {e}", file=sys.stderr)
+        return 1
     logging.basicConfig(
         level=logging.INFO, format="%(asctime)s %(levelname)s %(message)s"
     )

tests/test_cli.py

@@ -0,0 +1,48 @@
+import json
+
+import hookrelay.cli as cli
+
+BASE_CONFIG = {
+    "routes": [
+        {
+            "name": "r1",
+            "match": {"path": "/a"},
+            "sinks": [{"type": "generic", "url": "http://example.invalid"}],
+        }
+    ]
+}
+
+
+def _write_config(tmp_path, data):
+    p = tmp_path / "config.json"
+    p.write_text(json.dumps(data), encoding="utf-8")
+    return str(p)
+
+
+def test_run_missing_config_prints_clean_error(tmp_path, capsys):
+    missing = str(tmp_path / "does-not-exist.json")
+    rc = cli.main(["run", "-c", missing])
+    assert rc == 1
+    err = capsys.readouterr().err
+    assert "config error:" in err
+    assert "Traceback" not in err
+
+
+def test_run_invalid_config_prints_clean_error(tmp_path, capsys):
+    # missing required 'routes' key
+    path = _write_config(tmp_path, {})
+    rc = cli.main(["run", "-c", path])
+    assert rc == 1
+    err = capsys.readouterr().err
+    assert "config error:" in err
+    assert "Traceback" not in err
+
+
+def test_run_valid_config_starts_server(tmp_path, monkeypatch):
+    path = _write_config(tmp_path, BASE_CONFIG)
+    calls = []
+    monkeypatch.setattr(cli, "serve", lambda config: calls.append(config))
+    rc = cli.main(["run", "-c", path])
+    assert rc == 0
+    assert len(calls) == 1
+    assert calls[0].routes[0].name == "r1"