Older versions of Turf had two codes for the same mistake: E012 for a statement that comes after a return, break or continue, and E013 for a declaration in that position. In practice E012 always fired first, so E013 was documented and nobody ever saw it. The number is kept so an old log that mentions it still has somewhere to land, and is never reused.
Example
fn compute(): int { return 1; mut x: int = 5; // can never run -- E012}Run turf --explain E012 for the explanation and the fix: delete the code, or move it before the return.
Run turf --explain E013 in a terminal to read this again.