tests/cases/compiler/indexWithUndefinedAndNullStrictNullChecks.ts(9,19): error TS2454: Variable 'n' is used before being assigned.
tests/cases/compiler/indexWithUndefinedAndNullStrictNullChecks.ts(9,19): error TS2342: An index expression argument must be of type 'string', 'number', 'symbol', or 'any'.
tests/cases/compiler/indexWithUndefinedAndNullStrictNullChecks.ts(10,7): error TS2454: Variable 'n' is used before being assigned.
tests/cases/compiler/indexWithUndefinedAndNullStrictNullChecks.ts(10,7): error TS2342: An index expression argument must be of type 'string', 'number', 'symbol', or 'any'.
tests/cases/compiler/indexWithUndefinedAndNullStrictNullChecks.ts(11,19): error TS2454: Variable 's' is used before being assigned.
tests/cases/compiler/indexWithUndefinedAndNullStrictNullChecks.ts(11,19): error TS2342: An index expression argument must be of type 'string', 'number', 'symbol', or 'any'.
tests/cases/compiler/indexWithUndefinedAndNullStrictNullChecks.ts(12,7): error TS2454: Variable 's' is used before being assigned.
tests/cases/compiler/indexWithUndefinedAndNullStrictNullChecks.ts(12,7): error TS2342: An index expression argument must be of type 'string', 'number', 'symbol', or 'any'.


==== tests/cases/compiler/indexWithUndefinedAndNullStrictNullChecks.ts (8 errors) ====
    interface N {
        [n: number]: string;
    }
    interface S {
        [s: string]: number;
    }
    let n: N;
    let s: S;
    let str: string = n[undefined];
                      ~
!!! error TS2454: Variable 'n' is used before being assigned.
                      ~~~~~~~~~~~~
!!! error TS2342: An index expression argument must be of type 'string', 'number', 'symbol', or 'any'.
    str = n[null];
          ~
!!! error TS2454: Variable 'n' is used before being assigned.
          ~~~~~~~
!!! error TS2342: An index expression argument must be of type 'string', 'number', 'symbol', or 'any'.
    let num: number = s[undefined];
                      ~
!!! error TS2454: Variable 's' is used before being assigned.
                      ~~~~~~~~~~~~
!!! error TS2342: An index expression argument must be of type 'string', 'number', 'symbol', or 'any'.
    num = s[null];
          ~
!!! error TS2454: Variable 's' is used before being assigned.
          ~~~~~~~
!!! error TS2342: An index expression argument must be of type 'string', 'number', 'symbol', or 'any'.
    