Final answer:
Typically, an error is thrown when trying to output to a lookup that does not exist, and the system will notify the user or developer of the issue.
Step-by-step explanation:
If outputting to a lookup that does not exist, typically, an error is thrown. This means that when the code tries to access or write to a data structure or location that hasn't been defined or instantiated, most programming languages and systems will halt the process and generate an error message to notify the developer or user of the problem. The exact behavior can depend on the programming language and the context in which the output operation is performed. Some languages and systems might handle this gracefully and allow for the creation of the missing lookup (though this is not as common and usually requires explicit instructions in the code), while others will simply reject the operation and halt further execution of the program.