title: 'mat-expansion-panel' is not a known element when making build for production in angular 5
body: <p>I am using lazy loading in my Angular 5 project and I have imported 'mat-expansion-panel' in one of the module.
  'mat-expansion-panel' is working fine in development mode but when I make build for production it shows error that 'mat-expansion-panel' is not a known element without showing any line number.</p>
  
  <p>I searched everywhere but didn't found anything.</p>