Yes, that is a much better error message. Unfortunately it also tends to make functions much slower even when errors aren’t thrown because it creates a complex branch that captures all values that are used in the error message, which forces those values to be materialized and/or heap allocated. Using a static error message, on the other hand, has negligible performance impact, which is why so many error messages are like that. We have some newish technology to improve this, such as LazyString, but while that can help, it doesn’t entirely eliminate the problem. I’m planning on trying to make some better error messages like you suggest to see how bad the impact is and evaluate what kind of compiler magic we need to make it not affect performance unbearably, but it almost certainly will require some compiler work.