From 5a74d6f72f250361f19d71c384ce9aa35c234985 Mon Sep 17 00:00:00 2001
From: Lushiyao5 <321342421+Lushiyao5@users.noreply.github.com>
Date: Sat, 31 Oct 2026 11:31:17 -0500
Subject: [PATCH] Raise MalformedJSON for mismatched closing tokens

---
 src/partial_json_parser/core/myelin.py | 12 +++++++-----
 tests/test_examples.py                 |  8 ++++++++
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/src/partial_json_parser/core/myelin.py b/src/partial_json_parser/core/myelin.py
index 69bcd82..5f36438 100644
--- a/src/partial_json_parser/core/myelin.py
+++ b/src/partial_json_parser/core/myelin.py
@@ -4,7 +4,7 @@
 from typing import List, Tuple, Union
 
 from .complete import _fix
-from .exceptions import PartialJSON
+from .exceptions import MalformedJSON, PartialJSON
 from .options import *
 
 finditer = compile(r'["\[\]{}]').finditer
@@ -47,11 +47,13 @@ def is_escaped(index: int):
 
         elif not in_string:
             if char == "}":
-                _i, _char = stack.pop()
-                assert _char == "{", f"Expected '{{' at index {_i}, got '{_char}'"
+                if not stack or stack[-1][1] != "{":
+                    raise MalformedJSON(f"Unexpected token {char!r} at index {i}")
+                stack.pop()
             elif char == "]":
-                _i, _char = stack.pop()
-                assert _char == "[", f"Expected '[' at index {_i}, got '{_char}'"
+                if not stack or stack[-1][1] != "[":
+                    raise MalformedJSON(f"Unexpected token {char!r} at index {i}")
+                stack.pop()
             else:
                 stack.append((i, char))
 
diff --git a/tests/test_examples.py b/tests/test_examples.py
index 7bf8727..2c08fa3 100644
--- a/tests/test_examples.py
+++ b/tests/test_examples.py
@@ -95,6 +95,14 @@ def test_error():
         parse_json("--")
 
 
+def test_malformed_closing_tokens():
+    for json_string in ("]", "}", "[}", "{]", '{"a": 1]', "[1, 2}"):
+        with raises(MalformedJSON):
+            fix_fast(json_string)
+        with raises(MalformedJSON):
+            parse_json(json_string)
+
+
 def test_fix():
     assert fix("[") == fix_fast("[") == ("[", "]")
     assert fix("[0.") == fix_fast("[0.") == ("[0", "]")