Odd existence error for the (;)/2 control construct

With the following code (in a consulted source file):

logtalk_library_path(logtalk_home, '$LOGTALKHOME/').

% Logtalk user directory
logtalk_library_path(logtalk_user, '$LOGTALKUSER/').

% user home directory
logtalk_library_path(home, HOME) :-
	(	getenv('HOME', _) ->
		% likely a POSIX system but Windows users
		% may also define this environment variable
		HOME = '$HOME/'
	;	getenv('USERPROFILE', _) ->
		% Windows systems define this environment variable
		HOME = '$USERPROFILE/'
	;	fail
	).

And with the query:

logtalk_library_path(Library,_).

I get:

$ node ./tp.js 
Library = logtalk_home ;
Library = logtalk_user ;
uncaught exception: error(existence_error(procedure, /(;, 2)), /(logtalk_library_path, 2))
false.

The file compiles fine without any warnings or errors in the sandbox in the Tau Prolog website.

[pmoura]

Found the cause. Changing the code above by commenting the last require:

//require("./node_modules/tau-prolog/modules/system.js")(pl);

Allows the query to give all expected answers.

[pmoura]

Thanks for the quick reply. Closing.