Book Corner Sign

@@ -503,6 +503,9 @@ def self.current_context_index
  end
 
  def self.current_context
+ if ENV['files'] && @contexts.nil?
+ raise "Current context not set, perhaps there is an error in the file names you provided? (#{ENV['files'].join(',')}"
+ end
  @contexts[current_context_index]
  end