Array destructuring emits non-nullable types

[sberan]

With strictNullChecks: true, nullable values are not emitted as a result of an array destructure. Any array destructure can potentially emit undefined values.

TypeScript Version: 2.2.1

Code

  const x:number[] = []
  const [y] = x
  y.toString()

Expected behavior:
Compile error on line 3: [ts] Object is possibly 'undefined'

Actual behavior:
Runtime error on line 3: Cannot read property 'toString' of undefined

[jesseschalken]

See #11122 and related issues.

[sberan]

Thanks