Correct two stale comments in the jsonpull port

jsonpull.h said a json_number is 40 bytes; it is 32 (json_object is 24,
and the repr discriminator fits in the base class's tail padding, so the
8-byte union lands at offset 24).

plugin.cpp's parse_feature() said `j` is freed only just before returning
or as jp->root at end of stream, but there is a third json_free(j) at the
bottom of the loop, for a complete Feature whose geometry came out empty.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017KNxyHKasyWrWcvre2yK4r

jsonpull/jsonpull.h

@@ -111,7 +111,7 @@ struct json_object {
 	inline const std::string &string() const;
 
 	// Numbers are stored in a discriminated union (double / unsigned /
-	// signed) so a json_number is only 40 bytes instead of 48. The
+	// signed) so a json_number is only 32 bytes instead of 48. The
 	// large_*() accessors return 0 when the number is not currently
 	// stored in that representation, matching the prior convention
 	// where "0" meant "not set, fall through to the next slot".

plugin.cpp

@@ -151,9 +151,11 @@ serial_feature parse_feature(json_pull_ptr &jp, int z, unsigned x, unsigned y, s
 		// intermediate (still incomplete) container nodes. We must NOT free
 		// these intermediates here: they belong to the larger feature hash
 		// still being assembled, and freeing them would splice them out of
-		// the parent and corrupt the in-progress tree. We only free `j`
-		// after we have successfully processed a complete Feature hash
-		// (just before returning), or `jp->root` when the stream ends.
+		// the parent and corrupt the in-progress tree. So the `continue`
+		// paths below all leave `j` alone; `j` is only freed once it is a
+		// complete Feature hash -- either just before returning it, or at
+		// the bottom of the loop if its geometry turned out to be empty --
+		// or as `jp->root` when the stream ends.
 		json_object *j = json_read(jp);
 		if (j == nullptr) {
 			if (jp->error != nullptr) {