fix(awslambda): aws_event can be an empty list (#2849)

sentry_sdk/integrations/aws_lambda.py

@@ -81,7 +81,7 @@ def sentry_handler(aws_event, aws_context, *args, **kwargs):
         # will be the same for all events in the list, since they're all hitting
         # the lambda in the same request.)
 
-        if isinstance(aws_event, list):
+        if isinstance(aws_event, list) and len(aws_event) >= 1:
             request_data = aws_event[0]
             batch_size = len(aws_event)
         else:

tests/integrations/aws_lambda/test_aws.py

@@ -489,6 +489,7 @@ def test_handler(event, context):
             True,
             2,
         ),
+        (b"[]", False, 1),
     ],
 )
 def test_non_dict_event(