fix(list): handle cyclic reference when stringifying

src/core/list.py

@@ -14,6 +14,7 @@ if TYPE_CHECKING:
 class PebbleList(metaclass=BuiltinType):
     def __init__(self, items: Optional[list[Any]] = None):
         self.items: list[Any] = items or []
+        self._stringify_visited: bool = False
 
     def get(self, index: Any, bracket: Token):
         idx: int = Cast.as_int(bracket, index)
@@ -24,7 +25,12 @@ class PebbleList(metaclass=BuiltinType):
         self.items[idx] = value
 
     def __str__(self):
-        return "[" + ", ".join(map(lambda item: StringFormatter.stringify(item, True), self.items)) + "]"
+        if self._stringify_visited:
+            return "[...]"
+        self._stringify_visited = True
+        res: str = "[" + ", ".join(map(lambda item: StringFormatter.stringify(item, True), self.items)) + "]"
+        self._stringify_visited = False
+        return res
 
     # Exposed methods
     @exposed(nargs=1)