Fix lambda cannot be serialized. (#2102)

* Fix issue where a lambda cannot be serialized.

* Update changelog.

* Make format.

CHANGELOG.md

@@ -15,6 +15,7 @@ Copy and pasting the git commit messages is __NOT__ enough.
 ### Fixed
 - Fixed issue where `SumoTrafficSimulation` could get locked up on reset if a scenario had only 1 map but multiple scenario variations.
 - Fixed an issue where an out-of-scope method reference caused a pickling error.
+- Fixed an issue where the `EnvisionDataFormatterArgs` default would use a locally defined lambda and cause a serialization failure.
 ### Removed
 ### Security
 

envision/data_formatter.py

@@ -75,6 +75,10 @@ class Operation(IntEnum):
 _primitives = {int, float, str, VehicleType, TrafficActorType}
 
 
+def _passthrough_method_1_arg(v):
+    return v
+
+
 class ReductionContext:
     """Mappings between an object and its reduction to an ID."""
 
@@ -126,7 +130,7 @@ class EnvisionDataFormatterArgs(NamedTuple):
     """Data formatter configurations."""
 
     id: Optional[str]
-    serializer: Callable[[list], Any] = lambda d: d
+    serializer: Callable[[list], Any] = _passthrough_method_1_arg
     float_decimals: int = 2
     bool_as_int: bool = True
     enable_reduction: bool = True