title: Missing type annotation for `T`
body: <p>I am trying to build code with simple javascript function below:</p>
  
  <pre><code>filterArray(user: any, items: Array&lt;Object&gt;) {
      items = items.filter(item =&gt; {return true;});
      return items;
  }
  </code></pre>
  
  <p>But I am getting below error:</p>
  
  <pre><code>Missing type annotation for `T`. `T` is a type parameter declared in array type [1] and was implicitly instantiated at
  call of method `filter` [2].
  
     src/mod/test.js:69:15
     69|       items = items.filter(item =&gt; {return true;});
                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ [2]
  
  References:
     src/mod/test.js:69:15
     69|       items = items.filter(item =&gt; {return true;});
                       ^^^^^ [1]
  </code></pre>
  
  <p>I am using flow and building using npm.</p>