title: Does VSCode accurately display the correct Typescipt type in tooltip? no-unnecessary-type-assertion Error
body: <p>I'm trying to better understand <code>const assertions</code> in TS </p>
  
  <p>Consider the array <code>allDeviceTypes</code> in the image below, when i hover over the variable name  VSCode tells me that the return type is <code>string[]</code> </p>
  
  <p><a href="https://i.stack.imgur.com/gIYch.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/gIYch.png" alt="Typesciprt"></a></p>
  
  <p>However if I use a const assertion to narrow the type 
  I see the desired narrowed type but I'm met with the TSLint error: </p>
  
  <p><code>This assertion is unnecessary since it does not change the type of the expression. (no-unnecessary-type-assertion)tslint(1)</code></p>
  
  <p>So which is it? Is the type of the expression the same or is <code>VSCode 1.40.0</code>+ <code>TSlint 5.11.0</code> not displaying the right type in the tooltip?</p>
  
  <p><a href="https://i.stack.imgur.com/u5q7c.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/u5q7c.png" alt="enter image description here"></a></p>