Result summary widget is not handling None

[rsnyman]

ERROR in app: Exception on /api/widget/result-summary [GET]
Traceback (most recent call last):
File "/opt/app-root/lib64/python3.8/site-packages/flask/app.py", line 2525, in wsgi_app
response = self.full_dispatch_request()
File "/opt/app-root/lib64/python3.8/site-packages/flask/app.py", line 1822, in full_dispatch_request
rv = self.handle_user_exception(e)
File "/opt/app-root/lib64/python3.8/site-packages/flask_cors/extension.py", line 165, in wrapped_function
return cors_after_request(app.make_response(f(*args, **kwargs)))
File "/opt/app-root/lib64/python3.8/site-packages/flask/app.py", line 1820, in full_dispatch_request
rv = self.dispatch_request()
File "/opt/app-root/lib64/python3.8/site-packages/flask/app.py", line 1796, in dispatch_request
return self.ensure_sync(self.view_functions[rule.endpoint])(**view_args)
File "/opt/app-root/lib64/python3.8/site-packages/connexion/decorators/decorator.py", line 68, in wrapper
response = function(request)
File "/opt/app-root/lib64/python3.8/site-packages/connexion/security/security_handler_factory.py", line 388, in wrapper
return function(request)
File "/opt/app-root/lib64/python3.8/site-packages/connexion/decorators/uri_parsing.py", line 149, in wrapper
response = function(request)
File "/opt/app-root/lib64/python3.8/site-packages/connexion/decorators/validation.py", line 399, in wrapper
return function(request)
File "/opt/app-root/lib64/python3.8/site-packages/connexion/decorators/parameter.py", line 120, in wrapper
return function(**kwargs)
File "/opt/app-root/src/ibutsu_server/controllers/widget_controller.py", line 99, in get_widget
return WIDGET_METHODS[id_](**params)
File "/opt/app-root/src/ibutsu_server/widgets/result_summary.py", line 52, in get_result_summary
summary["error"] += error
TypeError: unsupported operand type(s) for +=: 'int' and 'NoneType'