message: Add change event type
diff: @@ -136,7 +136,7 @@ class UploadButton extends React.Component<IUploadButtonProps> {
  this.uploadInput.current.click();
  }
  - private onUploadFileInputChange = (ev) => {
  + private onUploadFileInputChange = (ev: React.ChangeEvent<HTMLInputElement>) => {
  if (ev.target.files.length === 0) return;
  // take a copy so we can safely reset the value of the form control
  