Still not at all clear to me how the one (experimental push issue) affects the other, but I'm unblocked from making progress. Any thoughts?

I don't know for sure, but I'd suspect that the earlier error caused the parser to get confused about the rest of the program, that kind of thing happens often - one syntax error can leave the parser in a bad state, and while it may try to parse the rest of the program to report as many other errors as it can, it obviously got it wrong in this case. That's why short yet complete examples like the one you showed (thank you for that) are always incredibly useful, since if we'd known there were other errors in addition to the one you stated in the root node, the fix would have probably become obvious faster.