Assertion failure SimplifiedFpGroup

[simpcomp-team]

Using SimplifiedFpGroup the following assertion error occurs with assertion level 2.

Observed behaviour

gap> SetAssertionLevel(2);
gap> g:=FreeGroup("a");
<free group on the generators [ a ]>
gap> gens:=GeneratorsOfGroup(g);
[ a ]
gap> rels:=[gens[1]];
[ a ]
gap> G:=g/rels;
<fp group on the generators [ a ]>
gap> SimplifiedFpGroup(G);
Error, Assertion failure in
  Assert( 2, ForAll( imgs, function ( x )
        return x in H;
    end ) ); at /home/jspreer/GAP/gap-repository/lib/ghom.gi:309 called from 
GroupGeneralMappingByImagesNC( G, H, gens, imgs 
 ) at /home/jspreer/GAP/gap-repository/lib/ghom.gi:439 called from
GroupHomomorphismByImagesNC( G, H, GeneratorsOfGroup( G ), 
 List( TzImagesOldGens( T ), function ( i )
        return MappedWord( i, GeneratorsOfPresentation( T ), 
           GeneratorsOfGroup( H ) );
    end ) ) at /home/jspreer/GAP/gap-repository/lib/tietze.gi:1214 called from
<function "SimplifiedFpGroup">( <arguments> )
 called from read-eval loop at *stdin*:6
you may 'return;'
brk> 

Expected behaviour

Should return trivial group (fp group with 0 generators).

GAP banner and loaded packages

GAP loaded with option -r.

 ┌───────┐   GAP 4.10dev-1285-g44f1a0c of today
 │  GAP  │   https://www.gap-system.org
 └───────┘   Architecture: x86_64-pc-linux-gnu-default64-kv5
 Configuration:  gmp 6.1.0, GASMAN, readline
 Loading the library and packages ...
 Packages:   AClib 1.3, Alnuth 3.1.0, AtlasRep 1.5.1, AutoDoc 2018.09.20, 
             AutPGrp 1.10, Browse 1.8.8, Carat 2.2.2, CRISP 1.4.4, 
             Cryst 4.1.17, CrystCat 1.1.8, CTblLib 1.2.2, FactInt 1.6.2, 
             FGA 1.4.0, GAPDoc 1.6.1, IO 4.5.4, IRREDSOL 1.4, LAGUNA 3.9.0, 
             Polenta 1.3.8, Polycyclic 2.14, PrimGrp 3.3.1, RadiRoot 2.8, 
             ResClasses 4.7.1, SmallGrp 1.3, Sophus 1.24, SpinSym 1.5, 
             TomLib 1.2.6, TransGrp 2.0.4, utils 0.58
 Try '??help' for help. See also '?copyright', '?cite' and '?authors'

[olexandr-konovalov]

Thanks. This issue comes from simpcomp-team/simpcomp#10. I can reproduce this with a fresh pull from the stable-4.10 branch.