Error message
In the message, %s marks a value that the engine fills in when it raises the error.
The story
You tried to put something into a collection, and the collection said, not this one. In rush, a list or a map has a shape, and the shape decides what it accepts. The judge is tungsten itself, the same single piece of logic used everywhere, not a custom check. The second part of the message is the collection's own verdict, in its own words. Two examples. If you write a list with a number and then a word, the collection says: value typing, heterogeneous insert into homogeneous shape. It was made to hold one kind and you mixed two. Or, if a bounded collection is already full, it says capacity: full. Here is why this message exists separately. It used to be reported as a parse problem, which pointed readers at the wrong stage, even though the verdict text was right there. A refusal should name the stage that refused, and this one comes from the collection at run time. So read the verdict, and then either change the member to fit the shape, or change the shape.
Text from the Rush engine's error catalogue.