parseNonNegativeInt function
Parses a non-negative integer or throws a FormatException.
Implementation
int parseNonNegativeInt(String val, String name) {
final parsed = int.tryParse(val);
if (parsed == null || parsed < 0) {
throw FormatException(
'Invalid $name: $val. Must be a non-negative integer.',
);
}
return parsed;
}