Orbital calculation error

@**Describe the bug** Orbital calculations using G-set do not work properly. **To Reproduce** Steps to reproduce the behavior, please provide a code snippet that triggers the bug. ``` lzm@lzm:/mnt/e/Article/Code/Oscar$ julia _ _ _ _(_)_ | Documentation: https://docs.julialang.org (_) | (_) (_) | _ _ _| |_ __ _ | Type "?" for help, "]?" for Pkg help. | | | | | | |/ _` | | | | |_| | | | (_| | | Version 1.12.6 (2026-04-09) _/ |\__'_|_|_|\__'_| | Official https://julialang.org release |__/ | julia> using Oscar ___ ___ ___ _ ____ / _ \ / __\ / __\ / \ | _ \ | Combining and extending ANTIC, GAP, | |_| |\__ \| |__ / ^ \ | ´ / | Polymake and Singular \___/ \___/ \___//_/ \_\|_|\_\ | Type "?Oscar" for more information o--------o-----o-----o--------o | Documentation: https://docs.oscar-system.org S Y M B O L I C T O O L S | Version 1.7.2 julia> g = dihedral_group(PermGroup, 20) Permutation group of degree 10 julia> h = sylow_subgroup(g, 2)[1] Permutation group of degree 10 and order 4 julia> g_set = gset(g, on_subgroups, [h]) G-set of permutation group of degree 10 with seeds [Permutation group of degree 10 and order 4] julia> orbits(g_set) ERROR: Error thrown by GAP: Error, <map> must be a general mapping at /home/lzm/.julia/artifacts/21532479477ddf5e931137aa39cb1e00a8edb15c/share/gap/lib/mapping.gi:100 called from <function "Image">( <arguments> ) called from read-eval loop at *defin*:0 Stacktrace: [1] error(s::String) @ Base ./error.jl:44 [2] ThrowObserver(depth::Int32) @ GAP ~/.julia/packages/GAP/yqI5E/src/errors.jl:44 [3] _call_gap_func @ ~/.julia/packages/GAP/yqI5E/src/ccalls.jl:367 [inlined] [4] (::GapObj)(a1::GapObj, a2::GapObj) @ GAP ~/.julia/packages/GAP/yqI5E/src/ccalls.jl:335 [5] Image @ ~/.julia/packages/Oscar/5rrcQ/src/GAP/wrappers.jl:161 [inlined] [6] on_subgroups @ ~/.julia/packages/Oscar/5rrcQ/src/Groups/action.jl:454 [inlined] [7] on_subgroups(x::PermGroup, g::PermGroupElem) @ Oscar ~/.julia/packages/Oscar/5rrcQ/src/Groups/action.jl:457 [8] orbit_via_Julia(Omega::Oscar.GSetByElements{PermGroup, PermGroup}, omega::PermGroup) @ Oscar ~/.julia/packages/Oscar/5rrcQ/src/Groups/gsets.jl:567 [9] orbit @ ~/.julia/packages/Oscar/5rrcQ/src/Groups/gsets.jl:556 [inlined] [10] __compute_orbits__(Omega::Oscar.GSetByElements{PermGroup, PermGroup}) @ Oscar ~/.julia/packages/Oscar/5rrcQ/src/Groups/gsets.jl:608 [11] #orbits##0 @ ~/.julia/packages/AbstractAlgebra/XwOtf/src/Attributes.jl:358 [inlined] [12] get!(default::Oscar.var"#orbits##0#orbits##1"{…}, h::Dict{…}, key::Symbol) @ Base ./dict.jl:458 [13] get_attribute!(f::Function, G::Oscar.GSetByElements{PermGroup, PermGroup}, attr::Symbol) @ AbstractAlgebra ~/.julia/packages/AbstractAlgebra/XwOtf/src/Attributes.jl:237 [14] orbits(Omega::Oscar.GSetByElements{PermGroup, PermGroup}) @ Oscar ~/.julia/packages/Oscar/5rrcQ/src/Groups/gsets.jl:603 [15] top-level scope @ REPL[5]:1 Some type information was truncated. Use `show(err)` to see complete types. julia> orbit(g_set, h) ERROR: Error thrown by GAP: Error, <map> must be a general mapping at /home/lzm/.julia/artifacts/21532479477ddf5e931137aa39cb1e00a8edb15c/share/gap/lib/mapping.gi:100 called from <function "Image">( <arguments> ) called from read-eval loop at *defin*:0 Stacktrace: [1] error(s::String) @ Base ./error.jl:44 [2] ThrowObserver(depth::Int32) @ GAP ~/.julia/packages/GAP/yqI5E/src/errors.jl:44 [3] _call_gap_func @ ~/.julia/packages/GAP/yqI5E/src/ccalls.jl:367 [inlined] [4] (::GapObj)(a1::GapObj, a2::GapObj) @ GAP ~/.julia/packages/GAP/yqI5E/src/ccalls.jl:335 [5] Image @ ~/.julia/packages/Oscar/5rrcQ/src/GAP/wrappers.jl:161 [inlined] [6] on_subgroups @ ~/.julia/packages/Oscar/5rrcQ/src/Groups/action.jl:454 [inlined] [7] on_subgroups(x::PermGroup, g::PermGroupElem) @ Oscar ~/.julia/packages/Oscar/5rrcQ/src/Groups/action.jl:457 [8] orbit_via_Julia(Omega::Oscar.GSetByElements{PermGroup, PermGroup}, omega::PermGroup) @ Oscar ~/.julia/packages/Oscar/5rrcQ/src/Groups/gsets.jl:567 [9] orbit(Omega::Oscar.GSetByElements{PermGroup, PermGroup}, omega::PermGroup) @ Oscar ~/.julia/packages/Oscar/5rrcQ/src/Groups/gsets.jl:556 [10] top-level scope @ REPL[6]:1 julia> ```