title: Typescript vue Object is possibly 'null'
body: <p>I have already checked the questions of the past, but I could not find a solution that worked for me. </p>
  
  <p>I am using Vue Typescript:</p>
  
  <pre><code>export default Vue.extend({
  
      data() {
        return {
          ...
          selectedOrder: null,
        };
      },
  
  
  
  approveOrder() {
          if(this.selectedOrder !== undefined &amp;&amp; this.selectedOrder!==null &amp;&amp; this.selectedOrder !== '') {
            let uri = 'http://localhost:8081/v1/order/approve/';
  
            uri = uri + this.selectedOrder.processInstanceId + '?approverId=' + this.getUser;
  </code></pre>
  
  <p>Error I get is:</p>
  
  <pre><code>164:21 Object is possibly 'null'.
      162 |           let uri = 'http://localhost:8081/v1/order/approve/';
      163 |
    &gt; 164 |           uri = uri + this.selectedOrder.processInstanceId + '?approverId=' + this.getUser;
          |                     ^
  </code></pre>