Sorted:

Devise: undefined method `user_signed_in?' for ApplicationController:Class-Collection of common programming errors

Function with missing return value, behavior at runtime-Collection of common programming errors

codeigniter modular seperation problem php mvc-Collection of common programming errors

I recieved this weird email today?-Collection of common programming errors

problem about gtk3-Collection of common programming errors

exception: Access violation-Collection of common programming errors

Can't open email in beta; can't change to classic; can't access help; error messages below:?-Collection of common programming errors

Organic groups organizational problem-Collection of common programming errors

Error Simple Login “undefined method `key?' for nil:NilClass”-Collection of common programming errors

GNUStep Undefined reference-Collection of common programming errors