In code blocks.
The overtype preview div has oveflow hidden so that you can't scroll to see the rest of the line.
The underlying textarea breaks text into multiple lines, getting the cursor out of sync.
sample code.
const giantTuple: [number, string, boolean, null, undefined, bigint, symbol, number[], {a: number; b: string}, (x: number) => string] = [42, "a very very very very very very very very very very very very very long string", true, null, undefined, 123456789012345678901234567890n, Symbol("sym"), [1,2,3,4,5,6,7,8,9,10], {a: 1, b: "long long long long long long value"}, (x) => `value is ${x}`];
In code blocks.
The overtype preview div has oveflow hidden so that you can't scroll to see the rest of the line.
The underlying textarea breaks text into multiple lines, getting the cursor out of sync.
sample code.