Got an error on deep_symbolize after authentication

[shioimm]

I am afraid that it is just a beginner's question but I got a trouble.
When I try to authenticate on a connection page, this error occured and I have no idea to solve it.
The error messages are:
undefined method 'inject' for nil:NilClass Did you mean? inspect
(omniauth-oauth2 (1.0.2) lib/omniauth/strategies/oauth2.rb:79:in 'deep_symbolize')

Could you tell me how can I solve this?
Thank you.