TypeError: can't convert nil into an exact number

[dblock]

E, [2018-11-21T02:36:57.172244 #236] ERROR -- : TypeError: can't convert nil into an exact number
  /app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.2.1/lib/active_support/core_ext/time/calculations.rb:53:in `at'
  /app/vendor/bundle/ruby/2.3.0/gems/activesupport-5.2.1/lib/active_support/core_ext/time/calculations.rb:53:in `at_with_coercion'
  /app/slack-strava/models/user.rb:99:in `connect!'
  /app/slack-strava/api/endpoints/users_endpoint.rb:18:in `block (2 levels) in <class:UsersEndpoint>'
  /app/vendor/bundle/ruby/2.3.0/gems/grape-1.1.0/lib/grape/endpoint.rb:57:in `call'
  /app/vendor/bundle/ruby/2.3.0/gems/grape-1.1.0/lib/grape/endpoint.rb:57:in `block (2 levels) in generate_api_method'