"Keys on Scalar" Syntax in json_server.pl Causes Fatal Error in Later Perl Versions

[JaredF]

MH will not startup using the version of Perl (v5.26.0) that ships with Ubuntu Artful (17.10) due to the following errors:

Experimental keys on scalar is now forbidden at /usr/local/bin/misterhouse/mh/bin/../lib/json_server.pl line 265.
Type of arg 1 to keys must be hash or array (not private variable) at /usr/local/bin/misterhouse/mh/bin/../lib/json_server.pl line 265, near "$body) "
Experimental keys on scalar is now forbidden at /usr/local/bin/misterhouse/mh/bin/../lib/json_server.pl line 266.
Type of arg 1 to keys must be hash or array (not hash element) at /usr/local/bin/misterhouse/mh/bin/../lib/json_server.pl line 266, near "}) "
Compilation failed in require at mh line 799.
 at mh line 31.
        main::__ANON__("Experimental keys on scalar is now forbidden at /usr/local/bi"...) called at mh line 799
        main::setup called at mh line 7770
mh rc=255
mh failed on startup ... will not restart