StrictNullCheck incorrectly prevents the use of the indexed access operator

[RainingChain]

TypeScript Version: 2.6.1

Code

class Klass {
  prop1:{innerNumber:number} | null;
  setInnerNumber(newInnerNumber:Klass['prop1']['innerNumber']){
    this.prop1 = {innerNumber:newInnerNumber}
  }
}
//Compile with --strictNullCheck

Expected behavior:
No error.

Actual behavior:
Property innerNumber does not exist on type '{ innerNumber:number;} | null'

Strict null check should not be checked for indexed access operator.

[ghost]

Duplicate of #14366

[typescript-bot]

Automatically closing this issue for housekeeping purposes. The issue labels indicate that it is unactionable at the moment or has already been addressed.

[mhegazy]

This should be doable today using NonNullable type