Copy-paste fix pattern
fn main() {
array scores = [10, 20, 30]
println(scores[0])
}Why it happens
Square brackets were used on a value that is not an array or string.
How to fix it
Only index arrays and strings. Convert the value or choose the correct variable before indexing.
Runtime and Studio now show this kind of page from the error dialog: plain message first, stable code second, original details third.