title: Why I am not getting warnings about StrictNullChecks in typescript
body: <p>I have the following code in typescript:</p>
  
  <pre><code>interface Member {
      name: string,
      age?: number
  }
  
  class Person implements Member {
      name: string;
      constructor(name: string ){
          this.name=name;
      }
  }
  
  function bar(person: Member) {
      return "Hello, " + person.name + " " + person.age;
  }
  
  let person = new Person("John");
  console.log(bar(person));
  </code></pre>
  
  <p>I am supposed to get <strong>Object is possibly 'undefined'</strong> warning inside bar function when i declare person.age since not every Member can have age. </p>
  
  <p>my typescript config looks like this:</p>
  
  <pre><code>{
    "compilerOptions": {
      "module": "commonjs",
      "target": "es5",
      "sourceMap": true,
      "strictNullChecks": true,
      "outDir": "./built"
    },
    "include": [
      "./src/**/*"
    ],
    "exclude": [
      "node_modules"
    ]
  }
  </code></pre>
  
  <p>Any idea why this is not working for me? I am using WebStorm Editor!</p>