Error message
In the message, %s marks a value that the engine fills in when it raises the error.
The story
Your script has an indentation problem, and in rush, that is not a matter of style. It is a parse error. The rule is exact: each level is four units deeper than the one around it. A space is worth one unit, and a tab is worth two. So four spaces work, two tabs work, and any mix that adds up to four works too. But a two space body does not, and neither does three spaces, nor a single tab. Also, when you go back out, you must land exactly on a level that is already open. There is no half way back. Why so strict? Because in rush, indentation is structure. A deeper line belongs to the header above it, and the engine cannot guess what you meant if the steps are uneven. The message tells you how many units the line stepped and what the law expected. The quick fix: set your editor to indent with four spaces. Then every body lines up, and the structure of your script will say exactly what you intend.
Text from the Rush engine's error catalogue.