Error Handling #73
Description
A consistent error handling system needs to be designed and implemented.
Currently each component has created error classes. Sometimes they are thrown, sometimes they are added to a list that is returned in a tuple along with the result. Their output format is inconsistent. They are currently all reported to stdout, and the exit value of the command is typically 0 unless an exception is not caught and then it's whatever Python says it is.
Each component is exposed to the Language Engineer through one or more CLI commands. These CLI commands may be wired together through Unix style pipes and filters, and so should follow standards and best practices related to Unix style command-line tools so that they integrate well with others. Here is a good resource.