It looks like the problem may actually be with ForAny. From what I can
see in the documentation, the following should work (returning false)
but does not. It's not clear that this is the same bug. The error
message is different.

gap> a:=[1,2];
[ 1, 2 ]
gap> ForAny([a,a,,,a,a],x->Length[x]>2);
Error, List Element: <position> must be a positive integer at
return Length[x] > 2 ... in
func( l ) called from
ForAny( [ a, a,,, a, a ], function ( x ) ... end ) called from
main loop
brk>