Comment by thomasrognon

You need

  "noUncheckedIndexedAccess": true

in your tsconfig.json. For odd only numbers, you can make a "branded" type. There are many options, one way is

  type OddNumber = number & { __BRAND_ODD_NUMBER: true }

then it's just

  OddNumber[]

and to onboard untrusted data, use a type guard

  const isOddNumber = (x: unknown): x is OddNumber => typeof x === 'number' && x % 2 === 1