Copy-paste fix pattern
fn main() {
u256 a = 10
u256 b = 20
save a + b
}Why it happens
Semicolons are optional at normal line ends, but compact one-line code can still need a separator.
How to fix it
Put each statement on its own line, or add semicolons when multiple statements share one line.
Runtime and Studio now show this kind of page from the error dialog: plain message first, stable code second, original details third.