title: mulFromInteger was called on null
body: <p>i have strange errors got from my flutter pages do some math computation with null value. or i assume it was makes errors happening.</p>
  
  <p>in my case i do computation such as (120 * null) inside stateful widget init section. when i build in release mode. I have debug view which means it read background in my apps and shows:</p>
  
  <pre><code>NoSuchMethodError: The method '_mulFromInteger' was called on null.
  Receiver: null
  Tried Calling:_mulFromInteger(134)
  </code></pre>
  
  <p>is multiply operations (*) have method  behind of it? or can anyone explain what is _mulFromInteger?</p>