TypeScript Version: 2.1.5 + http://www.typescriptlang.org/play/ both with strictNullChecks enabled

Code

// A *self-contained* demonstration of the problem follows...
interface ITest {
    key: string;
    values?: number[]
}

const t: ITest[] = [
    { key: 'key1', values: [] },
    { key: 'key2', values: [] }
];

for (const i of [1, 2, 3, 4, 5, 6, 7]) {
    t[0].values.push(i);
    t[1].values.push(i);
}

Expected behavior:

Since t[0] and t[1] have initialized values, I would expect that their type is number[]

Actual behavior:

I haven't found any workaround in which case t[0].values wouldn't be marked as possibly undefined anymore. Even if I set it right before the execution:

for (const i of [1, 2, 3, 4, 5, 6, 7]) {
    t[0].values = [];
    t[0].values.push(i);
}

I'm still getting the error that values might be undefined. My ugly workaround for now is to use 2 variables. Would it be possible to fix this in future versions of typescript?