diff --git a/dmcheck/cli.py b/dmcheck/cli.py
index a2c4cb9..5f68b66 100644
--- a/dmcheck/cli.py
+++ b/dmcheck/cli.py
@@ -207,10 +207,10 @@ def main(argv=None):
             ch["dice_authors"] = a.dice_bot
         transcript = load_transcript(a.transcript)
         ledger = load_ledger(a.ledger)
+        findings, code = check(transcript, ch, ledger)
     except (OSError, ValueError, json.JSONDecodeError) as e:
         print(json.dumps({"error": str(e)}), file=sys.stderr)
         return 2
-    findings, code = check(transcript, ch, ledger)
     print(json.dumps({"charter_version": ch.get("charter_version"),
                       "messages": len(transcript),
                       "findings": findings,
diff --git a/dmcheck/core.py b/dmcheck/core.py
index eb3915b..2a4e0b2 100644
--- a/dmcheck/core.py
+++ b/dmcheck/core.py
@@ -160,8 +160,8 @@ def check(transcript, charter, ledger=None, closed=True, now=None):
     enabled = set(ch.get("rules_enabled", list(RULES)))
     gm_idx = [r["i"] for r in T if _is_gm(r, ch)]
     if not ch["gm"]:
-        return [{"error": "charter names no GM author — cannot referee; "
-                          "set charter.gm or pass --gm"}], 2
+        raise ValueError("charter names no GM author — cannot referee; "
+                         "set charter.gm or pass --gm")
 
     # R1 unanswered-player: a non-GM, non-dice message containing a question,
     # with NO GM message in the next `answer_within_messages` messages.
diff --git a/dmcheck/watch.py b/dmcheck/watch.py
index e8a092a..bb6666d 100644
--- a/dmcheck/watch.py
+++ b/dmcheck/watch.py
@@ -112,6 +112,10 @@ def watch_main(a):
         ch["gm"] = a.gm
     if a.dice_bot:
         ch["dice_authors"] = a.dice_bot
+    if not ch.get("gm"):
+        print(json.dumps({"error": "charter names no GM author — cannot referee; "
+                                   "set charter.gm or pass --gm"}), file=sys.stderr)
+        return 2
     ledger = load_ledger(a.ledger)
     w = Watcher(ch, ledger, notify_cmd=a.notify_cmd,
                 craft=getattr(a, "craft", False), scene=getattr(a, "scene", "SOCIAL"),
diff --git a/tests/test_core.py b/tests/test_core.py
index 9b94780..6363ecc 100644
--- a/tests/test_core.py
+++ b/tests/test_core.py
@@ -58,11 +58,40 @@ def test_exit_code(self):
 
 class TestGuards(unittest.TestCase):
     def test_no_gm_declared_is_unusable(self):
+        """check() raises — it never returns a finding without a 'rule' key."""
         ch = load_charter(CH)
         ch["gm"] = []
-        findings, code = check(load_transcript(os.path.join(FIX, "clean-session.jsonl")), ch)
-        self.assertEqual(code, 2)
-        self.assertIn("error", findings[0])
+        with self.assertRaises(ValueError):
+            check(load_transcript(os.path.join(FIX, "clean-session.jsonl")), ch)
+
+    def test_cli_no_gm_is_exit_2_not_traceback(self):
+        """The 0.5.5 regression class: `dmcheck run <transcript>` with the
+        packaged default charter (no GM) must exit 2 with a JSON error on
+        stderr — never a KeyError traceback from the counts summary."""
+        import subprocess
+        r = subprocess.run(
+            [sys.executable, "-c",
+             "import sys; sys.path.insert(0, %r); from dmcheck.cli import main; "
+             "sys.argv = ['dmcheck', 'run', %r]; sys.exit(main())"
+             % (os.path.join(os.path.dirname(__file__), ".."),
+                os.path.join(FIX, "clean-session.jsonl"))],
+            capture_output=True, text=True)
+        self.assertEqual(r.returncode, 2, r.stderr)
+        self.assertNotIn("Traceback", r.stderr)
+        err = json.loads(r.stderr.strip().splitlines()[-1])
+        self.assertIn("no GM author", err["error"])
+
+    def test_watch_no_gm_is_exit_2(self):
+        import subprocess
+        r = subprocess.run(
+            [sys.executable, "-c",
+             "import sys; sys.path.insert(0, %r); from dmcheck.cli import main; "
+             "sys.argv = ['dmcheck', 'watch', %r]; sys.exit(main())"
+             % (os.path.join(os.path.dirname(__file__), ".."),
+                os.path.join(FIX, "clean-session.jsonl"))],
+            capture_output=True, text=True)
+        self.assertEqual(r.returncode, 2, r.stderr)
+        self.assertNotIn("Traceback", r.stderr)
 
 
 if __name__ == "__main__":