private void assertValid() {
    Segment hostRange = relevantRangeInHost.getPsiRange();
    assert hostRange != null : "invalid host range: " + relevantRangeInHost;

    PsiLanguageInjectionHost host = hostElementPointer.getElement();
    assert host != null && host.isValid() : "no host: " + hostElementPointer;
  }
private void assertValid()