[user]. Syntax error not reported

[flexoron]

?- [user].
{x|y|z}.
?- X =.. [{},(A|B|C)], call(X).
   error(syntax_error(incomplete_reduction),read_term/3:1). % unexpected
   X = {x|y|z}, A = x, B = y, C = z. % expected but not found.
?-