142. Subject to the provisions of the second paragraph of this section, any person other than the defendant, examined as a witness in any prosecution under this act, shall be obliged to answer all questions put to him and judged pertinent to the issue, even if such answers may reveal facts tending to make him liable to any penalty imposed by this act; but such evidence cannot be adduced against him in any prosecution.
No witness examined in any prosecution under this act can be compelled to say if he is the informer in such prosecution. Nor shall any question be put to him with the object of showing that the prosecution was taken on a complaint by an informer, or calculated to reveal the name of the informer.