If you encountered TypeScript errors of the following form after installing 6.2.0 or 6.2.1,

tests/integration/components/my-component.ts:59:23 - error TS2345: Argument of type 'string | SafeString' is not assignable to parameter of type 'string'.
  Type 'SafeString' is not assignable to type 'string'.

59   .hasText(t('some.key'));

please try installing 6.2.2 instead. As a temporary fix, I cast the return type of the test helper t() to be string.