When Hyrax 1.16 runs, we see some error messages 'leaking out of stderr'
These messages are all "syntax error" (lower case) and appear to be from the bison parsers.
e.g. d4_ce_parser.tab.cc lines 1516:
This seems to alway appear inside code surrounded by ‘#if YYERROR_VERBOSE … #endif' So there might be a parser built that way and causing these meesages
add #define YYERROR_VERBOSE 0 to *.yy files so output is suppressed