NoMethodError: undefined method `+' for nil:NilClass #20
Description
Check full details on Airbrake: https://concordconsortium.airbrake.io/projects/89269/groups/67988483?auth_token=d03078140ac54d4996fd39f66bcf6c8675e9097b
[PROJECT_ROOT]/app/models/embeddable/answer.rb:4:in question_index
[PROJECT_ROOT]/app/views/embeddable/multiple_choice_answers/_lightweight.html.haml:4:in _app_views_embeddable_multiple_choice_answers__lightweight_html_haml__2751643300114585755_44615100
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/template.rb:145:in block in render
[GEM_ROOT]/gems/activesupport-3.2.13/lib/active_support/notifications.rb:125:in instrument
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/template.rb:143:in render
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/renderer/partial_renderer.rb:265:in render_partial
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/renderer/partial_renderer.rb:238:in block in render
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/renderer/abstract_renderer.rb:38:in block in instrument
[GEM_ROOT]/gems/activesupport-3.2.13/lib/active_support/notifications.rb:123:in block in instrument
[GEM_ROOT]/gems/activesupport-3.2.13/lib/active_support/notifications/instrumenter.rb:20:in instrument
[GEM_ROOT]/gems/activesupport-3.2.13/lib/active_support/notifications.rb:123:in instrument
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/renderer/abstract_renderer.rb:38:in instrument
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/renderer/partial_renderer.rb:237:in render
[GEM_ROOT]/gems/newrelic_rpm-3.6.7.159/lib/new_relic/agent/instrumentation/rails3/action_controller.rb:176:in block in render_with_newrelic
[GEM_ROOT]/gems/newrelic_rpm-3.6.7.159/lib/new_relic/agent/method_tracer.rb:259:in trace_execution_scoped
[GEM_ROOT]/gems/newrelic_rpm-3.6.7.159/lib/new_relic/agent/instrumentation/rails3/action_controller.rb:175:in render_with_newrelic
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/renderer/renderer.rb:41:in render_partial
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/renderer/renderer.rb:15:in render
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/helpers/rendering_helper.rb:24:in render
[GEM_ROOT]/gems/haml-4.0.3/lib/haml/helpers/action_view_mods.rb:10:in block in render_with_haml
[GEM_ROOT]/gems/haml-4.0.3/lib/haml/helpers.rb:89:in non_haml
[GEM_ROOT]/gems/haml-4.0.3/lib/haml/helpers/action_view_mods.rb:10:in render_with_haml
[PROJECT_ROOT]/app/views/interactive_pages/_list_embeddables.html.haml:5:in block in _app_views_interactive_pages__list_embeddables_html_haml__484224522061471133_41101160
[PROJECT_ROOT]/app/views/interactive_pages/_list_embeddables.html.haml:3:in each
[PROJECT_ROOT]/app/views/interactive_pages/_list_embeddables.html.haml:3:in _app_views_interactive_pages__list_embeddables_html_haml__484224522061471133_41101160
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/template.rb:145:in block in render
[GEM_ROOT]/gems/activesupport-3.2.13/lib/active_support/notifications.rb:125:in instrument
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/template.rb:143:in render
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/renderer/partial_renderer.rb:265:in render_partial
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/renderer/partial_renderer.rb:238:in block in render
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/renderer/abstract_renderer.rb:38:in block in instrument
[GEM_ROOT]/gems/activesupport-3.2.13/lib/active_support/notifications.rb:123:in block in instrument
[GEM_ROOT]/gems/activesupport-3.2.13/lib/active_support/notifications/instrumenter.rb:20:in instrument
[GEM_ROOT]/gems/activesupport-3.2.13/lib/active_support/notifications.rb:123:in instrument
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/renderer/abstract_renderer.rb:38:in instrument
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/renderer/partial_renderer.rb:237:in render
[GEM_ROOT]/gems/newrelic_rpm-3.6.7.159/lib/new_relic/agent/instrumentation/rails3/action_controller.rb:176:in block in render_with_newrelic
[GEM_ROOT]/gems/newrelic_rpm-3.6.7.159/lib/new_relic/agent/method_tracer.rb:259:in trace_execution_scoped
[GEM_ROOT]/gems/newrelic_rpm-3.6.7.159/lib/new_relic/agent/instrumentation/rails3/action_controller.rb:175:in render_with_newrelic
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/renderer/renderer.rb:41:in render_partial
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/renderer/renderer.rb:15:in render
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/helpers/rendering_helper.rb:24:in render
[GEM_ROOT]/gems/haml-4.0.3/lib/haml/helpers/action_view_mods.rb:10:in block in render_with_haml
[GEM_ROOT]/gems/haml-4.0.3/lib/haml/helpers.rb:89:in non_haml
[GEM_ROOT]/gems/haml-4.0.3/lib/haml/helpers/action_view_mods.rb:10:in render_with_haml
[PROJECT_ROOT]/app/views/interactive_pages/show.html.haml:22:in _app_views_interactive_pages_show_html_haml__3499644302362358594_42547940
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/template.rb:145:in block in render
[GEM_ROOT]/gems/activesupport-3.2.13/lib/active_support/notifications.rb:125:in instrument
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/template.rb:143:in render
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/renderer/template_renderer.rb:47:in block (2 levels) in render_template
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/renderer/abstract_renderer.rb:38:in block in instrument
[GEM_ROOT]/gems/activesupport-3.2.13/lib/active_support/notifications.rb:123:in block in instrument
[GEM_ROOT]/gems/activesupport-3.2.13/lib/active_support/notifications/instrumenter.rb:20:in instrument
[GEM_ROOT]/gems/activesupport-3.2.13/lib/active_support/notifications.rb:123:in instrument
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/renderer/abstract_renderer.rb:38:in instrument
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/renderer/template_renderer.rb:46:in block in render_template
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/renderer/template_renderer.rb:54:in render_with_layout
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/renderer/template_renderer.rb:45:in render_template
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/renderer/template_renderer.rb:18:in render
[GEM_ROOT]/gems/newrelic_rpm-3.6.7.159/lib/new_relic/agent/instrumentation/rails3/action_controller.rb:160:in block in render_with_newrelic
[GEM_ROOT]/gems/newrelic_rpm-3.6.7.159/lib/new_relic/agent/method_tracer.rb:259:in trace_execution_scoped
[GEM_ROOT]/gems/newrelic_rpm-3.6.7.159/lib/new_relic/agent/instrumentation/rails3/action_controller.rb:159:in render_with_newrelic
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/renderer/renderer.rb:36:in render_template
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_view/renderer/renderer.rb:17:in render
[GEM_ROOT]/gems/actionpack-3.2.13/lib/abstract_controller/rendering.rb:110:in _render_template
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_controller/metal/streaming.rb:225:in _render_template
[GEM_ROOT]/gems/actionpack-3.2.13/lib/abstract_controller/rendering.rb:103:in render_to_body
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_controller/metal/renderers.rb:28:in render_to_body
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_controller/metal/compatibility.rb:50:in render_to_body
[GEM_ROOT]/gems/actionpack-3.2.13/lib/abstract_controller/rendering.rb:88:in render
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_controller/metal/rendering.rb:16:in render
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_controller/metal/instrumentation.rb:40:in block (2 levels) in render
[GEM_ROOT]/gems/activesupport-3.2.13/lib/active_support/core_ext/benchmark.rb:5:in block in ms
/usr/local/lib/ruby/1.9.1/benchmark.rb:295:in realtime
[GEM_ROOT]/gems/activesupport-3.2.13/lib/active_support/core_ext/benchmark.rb:5:in ms
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_controller/metal/instrumentation.rb:40:in block in render
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_controller/metal/instrumentation.rb:83:in cleanup_view_runtime
[GEM_ROOT]/gems/activerecord-3.2.13/lib/active_record/railties/controller_runtime.rb:24:in cleanup_view_runtime
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_controller/metal/instrumentation.rb:39:in render
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_controller/metal/implicit_render.rb:10:in default_render
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_controller/metal/mime_responds.rb:196:in respond_to
[PROJECT_ROOT]/app/controllers/interactive_pages_controller.rb:23:in show
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_controller/metal/implicit_render.rb:4:in send_action
[GEM_ROOT]/gems/actionpack-3.2.13/lib/abstract_controller/base.rb:167:in process_action
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_controller/metal/rendering.rb:10:in process_action
[GEM_ROOT]/gems/actionpack-3.2.13/lib/abstract_controller/callbacks.rb:18:in block in process_action
[GEM_ROOT]/gems/activesupport-3.2.13/lib/active_support/callbacks.rb:447:in _run__73154131152327254__process_action__4459830708283182803__callbacks
[GEM_ROOT]/gems/activesupport-3.2.13/lib/active_support/callbacks.rb:405:in __run_callback
[GEM_ROOT]/gems/activesupport-3.2.13/lib/active_support/callbacks.rb:385:in _run_process_action_callbacks
[GEM_ROOT]/gems/activesupport-3.2.13/lib/active_support/callbacks.rb:81:in run_callbacks
[GEM_ROOT]/gems/actionpack-3.2.13/lib/abstract_controller/callbacks.rb:17:in process_action
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_controller/metal/rescue.rb:29:in process_action
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_controller/metal/instrumentation.rb:30:in block in process_action
[GEM_ROOT]/gems/activesupport-3.2.13/lib/active_support/notifications.rb:123:in block in instrument
[GEM_ROOT]/gems/activesupport-3.2.13/lib/active_support/notifications/instrumenter.rb:20:in instrument
[GEM_ROOT]/gems/activesupport-3.2.13/lib/active_support/notifications.rb:123:in instrument
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_controller/metal/instrumentation.rb:29:in process_action
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_controller/metal/params_wrapper.rb:207:in process_action
[GEM_ROOT]/gems/activerecord-3.2.13/lib/active_record/railties/controller_runtime.rb:18:in process_action
[GEM_ROOT]/gems/newrelic_rpm-3.6.7.159/lib/new_relic/agent/instrumentation/rails3/action_controller.rb:38:in block in process_action
[GEM_ROOT]/gems/newrelic_rpm-3.6.7.159/lib/new_relic/agent/instrumentation/controller_instrumentation.rb:324:in perform_action_with_newrelic_trace
[GEM_ROOT]/gems/newrelic_rpm-3.6.7.159/lib/new_relic/agent/instrumentation/rails3/action_controller.rb:37:in process_action
[GEM_ROOT]/gems/actionpack-3.2.13/lib/abstract_controller/base.rb:121:in process
[GEM_ROOT]/gems/actionpack-3.2.13/lib/abstract_controller/rendering.rb:45:in process
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_controller/metal.rb:203:in dispatch
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_controller/metal/rack_delegation.rb:14:in dispatch
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_controller/metal.rb:246:in block in action
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_dispatch/routing/route_set.rb:73:in call
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_dispatch/routing/route_set.rb:73:in dispatch
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_dispatch/routing/route_set.rb:36:in call
[GEM_ROOT]/gems/journey-1.0.4/lib/journey/router.rb:68:in block in call
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[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_dispatch/routing/route_set.rb:612:in call
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[GEM_ROOT]/gems/newrelic_rpm-3.6.7.159/lib/new_relic/rack/browser_monitoring.rb:16:in call
[GEM_ROOT]/gems/rack-plastic-0.1.3/lib/plastic_helper.rb:25:in handle_request
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[GEM_ROOT]/gems/rack-1.4.5/lib/rack/conditionalget.rb:25:in call
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[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_dispatch/middleware/flash.rb:242:in call
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[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_dispatch/middleware/cookies.rb:341:in call
[GEM_ROOT]/gems/activerecord-3.2.13/lib/active_record/query_cache.rb:64:in call
[GEM_ROOT]/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:479:in call
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_dispatch/middleware/callbacks.rb:28:in block in call
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[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_dispatch/middleware/remote_ip.rb:31:in call
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_dispatch/middleware/debug_exceptions.rb:16:in call
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_dispatch/middleware/show_exceptions.rb:56:in call
[GEM_ROOT]/gems/railties-3.2.13/lib/rails/rack/logger.rb:32:in call_app
[GEM_ROOT]/gems/railties-3.2.13/lib/rails/rack/logger.rb:16:in block in call
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[GEM_ROOT]/gems/railties-3.2.13/lib/rails/rack/logger.rb:16:in call
[GEM_ROOT]/gems/actionpack-3.2.13/lib/action_dispatch/middleware/request_id.rb:22:in call
[GEM_ROOT]/gems/rack-1.4.5/lib/rack/methodoverride.rb:21:in call
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[GEM_ROOT]/gems/activesupport-3.2.13/lib/active_support/cache/strategy/local_cache.rb:72:in call
[GEM_ROOT]/gems/rack-1.4.5/lib/rack/lock.rb:15:in call
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[GEM_ROOT]/gems/rack-cache-1.2/lib/rack/cache/context.rb:66:in call!
[GEM_ROOT]/gems/rack-cache-1.2/lib/rack/cache/context.rb:51:in call
[GEM_ROOT]/gems/railties-3.2.13/lib/rails/engine.rb:479:in call
[GEM_ROOT]/gems/railties-3.2.13/lib/rails/application.rb:223:in call
[GEM_ROOT]/gems/railties-3.2.13/lib/rails/railtie/configurable.rb:30:in method_missing
[GEM_ROOT]/gems/shutterbug-0.1.1/lib/shutterbug/rackapp.rb:60:in skip
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/usr/local/lib/ruby/gems/1.9.1/gems/passenger-3.0.12/lib/phusion_passenger/abstract_server_collection.rb:82:in block in synchronize
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/usr/local/lib/ruby/gems/1.9.1/gems/passenger-3.0.12/helper-scripts/passenger-spawn-server:99:in <main>