Setting a value inside a find() results in a type being incorrectly narrowed

[M-Garrett]

TypeScript Version:
3.9.2

Code

interface example { 
  num: string
  val: string
}
const examples = [
  { num: '1', val: 'A' }, 
  { num: '2', val: 'B' },
  { num: '3', val: 'C' },
]
let a: example | null = null
examples.find(t => { 
  a = t
  return t.num === '2'
})
// a is { num: '2', val: 'B' } 
// but the next line thinks it is of type null and shows compiler errors
if (a !== null && a.num === '2') {
  alert(a.val)
}

Expected behaviour:
No TS errors.

Actual behaviour:
Once it reaches the if, TS thinks that a must be null, despite it's assignment inside the .find(). After the a !== null, a is assumed to be never and prop access causes errors.

Playground Link:
Playground link

[MartinJohns]

Duplicate of #9998.