That is what’s rare, but you’re missing something important: the reason the repeated noun is there to begin with is to avoid ambiguity about what, exactly, is b

That is what’s rare, but you’re missing something important: the reason the repeated noun is there to begin with is to avoid ambiguity about what, exactly, is being granted, since there are multiple available antecedents. The errors? No, the motion. In other words, the noun isn’t implicit, or at least not adequately implicit. Even in 1934, you didn’t think of it as eliding the noun when you used “which” as a pronoun; rather, you thought of using the noun again as an escape hatch for ugly situations like this. More to the point, in modern English, where we don’t have this option, we’d have to restructure the sentence to avoid this ambiguity, not simply drop the noun.