Typescript Errors while converting a React project
<p>This is specific to a React app I am converting from standard ES2015 to Typescript. In my .tsx files (converted from regular .js files) I am getting a couple of typescript errors I do not know how to solve.</p>

<p>The first is: <code>error TS2339: Property 'propTypes' does not exist on type 'typeof App'.</code></p>

<p>This applies to:</p>

<pre><code>App.propTypes = {
  actions: PropTypes.object.isRequired,
  fuelSavingsAppState: PropTypes.object.isRequired
};
</code></pre>

<p>I tried creating an interface above that code that defined App like:</p>

<pre><code>interface App {
    propTypes?: any;
}
</code></pre>

<p>But this had no effect. Clearly I am new to Typescript so what am I missing?</p>

<p>The other error is: </p>

<pre><code>error TS2605: JSX element type 'Element' is not a constructor function for JSX elements.
  Property 'render' is missing in type 'Element'
</code></pre>

<p>and this applies to:</p>

<pre><code>{settings.necessaryDataIsProvidedToCalculateSavings ? &lt;FuelSavingsResults savings={settings.savings} /&gt; : null}
</code></pre>

<p>The error specifically refers to the bit about <code>&lt;FuelSavingsResults</code> </p>

<p>At a complete loss as to where to even start with that. Any suggestions are most welcome.</p>

<hr>

<p>in case it helps, the definition for FuelSavingsResults starts like:</p>

<pre><code>let FuelSavingsResults = (props) =&gt; {
    let savingsExist = NumberFormatter.scrubFormatting(props.savings.monthly) &gt; 0;
    let savingsClass = savingsExist ? 'savings' : 'loss';
    let resultLabel = savingsExist ? 'Savings' : 'Loss';
</code></pre>

<p>and then has a regular React render method that follows, but I don't think that will matter.</p>