Run-time problem

P50 - Attempt to use list item which does not exist

Most problems are detected when Inform translates the source text, but this is one of the exceptions, a "run-time problem" which emerges only during play.

This is fairly self-explanatory. The problem might occur if we tried to insert something after item 10 in a list which only contains six items, for instance, or to remove the value 230 from a list of numbers which does not contain 230 anywhere.