Migration Plugin

Just an extra comma will do.

http POST :/pulp/api/v3/migration-plans/  plan='{"plugins": [{"type": "iso"},]}'

[11951]: 127.0.0.1 - admin [08/Dec/2020:10:40:07 +0000] "POST /pulp/api/v3/migration-plans/ HTTP/1.1" 500 27 "-" "HTTPie/2.3.0"
[11951]: pulp [4bf9ea0a47ee43dd804b8e930aef0710]: django.request:ERROR: Internal Server Error: /pulp/api/v3/migration-plans/
[11951]: Traceback (most recent call last):
[11951]: File "/usr/local/lib/pulp/lib64/python3.6/site-packages/django/core/handlers/exception.py", line 34, in inner
[11951]: response = get_response(request)
[11951]: File "/usr/local/lib/pulp/lib64/python3.6/site-packages/django/core/handlers/base.py", line 115, in _get_response
[11951]: response = self.process_exception_by_middleware(e, request)
[11951]: File "/usr/local/lib/pulp/lib64/python3.6/site-packages/django/core/handlers/base.py", line 113, in _get_response
[11951]: response = wrapped_callback(request, *callback_args, **callback_kwargs)
[11951]: File "/usr/local/lib/pulp/lib64/python3.6/site-packages/django/views/decorators/csrf.py", line 54, in wrapped_view
[11951]: return view_func(*args, **kwargs)
[11951]: File "/usr/local/lib/pulp/lib64/python3.6/site-packages/rest_framework/viewsets.py", line 125, in view
[11951]: return self.dispatch(request, *args, **kwargs)
[11951]: File "/usr/local/lib/pulp/lib64/python3.6/site-packages/rest_framework/views.py", line 509, in dispatch
[11951]: response = self.handle_exception(exc)
[11951]: File "/usr/local/lib/pulp/lib64/python3.6/site-packages/rest_framework/views.py", line 469, in handle_exception
[11951]: self.raise_uncaught_exception(exc)
[11951]: File "/usr/local/lib/pulp/lib64/python3.6/site-packages/rest_framework/views.py", line 480, in raise_uncaught_exception
[11951]: raise exc
[11951]: File "/usr/local/lib/pulp/lib64/python3.6/site-packages/rest_framework/views.py", line 506, in dispatch
[11951]: response = handler(request, *args, **kwargs)
[11951]: File "/usr/local/lib/pulp/lib64/python3.6/site-packages/rest_framework/mixins.py", line 18, in create
[11951]: serializer.is_valid(raise_exception=True)
[11951]: File "/usr/local/lib/pulp/lib64/python3.6/site-packages/rest_framework/serializers.py", line 220, in is_valid
[11951]: self._validated_data = self.run_validation(self.initial_data)
[11951]: File "/usr/local/lib/pulp/lib64/python3.6/site-packages/rest_framework/serializers.py", line 422, in run_validation
[11951]: value = self.validate(value)
[11951]: File "/home/vagrant/devel/pulp-2to3-migration/pulp_2to3_migration/app/serializers.py", line 63, in validate
[11951]: loaded_plan = json.loads(data['plan'])
[11951]: File "/usr/lib64/python3.6/json/__init__.py", line 354, in loads
[11951]: return _default_decoder.decode(s)
[11951]: File "/usr/lib64/python3.6/json/decoder.py", line 339, in decode
[11951]: obj, end = self.raw_decode(s, idx=_w(s, 0).end())
[11951]: File "/usr/lib64/python3.6/json/decoder.py", line 355, in raw_decode
[11951]: obj, end = self.scan_once(s, idx)
[11951]: json.decoder.JSONDecodeError: Expecting ',' delimiter: line 1 column 29 (char 28)

Pulp should error stating that it's syntax problem and propagate the exception all the way up to the user.