The JavaScript exception "x can't be converted to BigInt because it isn't an integer" occurs when the BigInt() function is used on a number that isn't an integer.
Message
RangeError: The number 1.5 cannot be converted to a BigInt because it is not an integer (V8-based & Firefox)
RangeError: Not an integer (Safari)
Error type
What went wrong?
When using the BigInt() function to convert a number to a BigInt, the number must be an integer (such that Number.isInteger returns true).
Examples
Invalid cases
const a = BigInt(1.5);
// RangeError: The number 1.5 cannot be converted to a BigInt because it is not an integer
const b = BigInt(NaN);
// RangeError: NaN cannot be converted to a BigInt because it is not an integer
Valid cases
const a = BigInt(1);