title: Error reading file: Type of 'await' operand must either be a valid promise or must not contain a callable 'then' member
body: <p>I have the error: 'Type of 'await' operand must either be a valid promise or must not contain a callable 'then' member.' when changing the format of a test from using promise .then() based syntax which worked to use async/await. Which was my attempt below.</p>
  <pre class="lang-js prettyprint-override"><code> it('downloads successfully', async () =&gt; {
          cy.get(downloadButton).click();
  
          const csv = await cy.readFile(filename, { timeout: 15000 });
          csv.should('have.length.gt', 20);
          expect(csv, 'number of records').to.have.length(10);
  })
  </code></pre>
  <p>before</p>
  <pre class="lang-js prettyprint-override"><code>cy.readFile(filename, { timeout: 15000 })
            .should('have.length.gt', 20)
            .then(validateCsv);
  
  </code></pre>