Error in C6 recognition

[ssiccha]

When running the following loop sufficiently often, recog runs into an error in its C6 recognition method.

gap> testFDPM := function(deg, field, alternating)
> local g, gens, mgens, m, cf, dims, max, pos, x, h, result;
> if alternating then
>   g := AlternatingGroup(deg);
> else
>   g := SymmetricGroup(deg);
> fi;
> gens := List([1..5],x->PseudoRandom(g));
> mgens := List(gens,x->PermutationMat(x,deg,field));
> m := GModuleByMats(mgens,field);
> cf := MTX.CompositionFactors(m);
> dims := List(cf,x->x.dimension);
> max := Maximum(dims);
> pos := Position(dims,max);
> x := PseudoRandom(GL(max,field));
> mgens := List(cf[pos].generators,y->y^x);
> h := Group(mgens);
> return Size(RecogniseGroup(h)) = Size(g);
> #return RECOG.TestGroup(h,false,Size(g));
> end;;
gap> while true do
> testFDPM(10, GF(7), bool);
> bool := not bool;
> od;

F dim=   9 field=7  0
F dim=   9 field=7  0
Error, what's wrong2? at /home/sergio/projects/pkg/recog/gap/projective/c6.gi:183
RECOG.RadBasis( r, n, q, rad ) at /home/sergio/projects/pkg/recog/gap/projective/
RECOG.basis2( r, n, q, rgrp ) at /home/sergio/projects/pkg/recog/gap/projective/c
RECOG.New2RecogniseC6( G ) at /home/sergio/projects/pkg/recog/gap/projective/c6.g
CallFuncList( UnpackRecogMethod( m ), args ) at /home/sergio/projects/pkg/recog/g
CallRecogMethod( db[i].method, methargs ) at /home/sergio/projects/pkg/recog/gap/
...  at *stdin*:35
type 'quit;' to quit to outer loop

[fingolfin]

Here is code to reproduce the code immediately, without waiting for a loop:

Reset(GlobalMersenneTwister, 220);
Reset(GlobalRandomSource, 220);
deg := 10;
field := GF(7);
g := AlternatingGroup(deg);
gens := List([1..5],x->PseudoRandom(g));
mgens := List(gens,x->PermutationMat(x,deg,field));
m := GModuleByMats(mgens,field);
cf := MTX.CompositionFactors(m);
dims := List(cf,x->x.dimension);
max := Maximum(dims);
pos := Position(dims,max);
x := PseudoRandom(GL(max,field));
mgens := List(cf[pos].generators,y->y^x);
h := Group(mgens);
Size(RecogniseGroup(h)) = Size(g);