  We present the implementation of general-relativistic resistive
magnetohydrodynamics solvers and three divergence-free handling approaches
adopted in the General-relativistic multigrid numerical (Gmunu) code.
  In particular, implicit-explicit Runge-Kutta schemes are used to deal with
the stiff terms in the evolution equations for small resistivity.
  Three divergence-free handling methods are (i) hyperbolic divergence cleaning
through a generalised Lagrange multiplier (GLM); (ii) staggered-meshed
constrained transport (CT) schemes and (iii) elliptic cleaning though multigrid
(MG) solver which is applicable in both cell-centred and face-centred (stagger
grid) magnetic field.
  The implementation has been test with a number of numerical benchmarks from
special-relativistic to general-relativistic cases.
  We demonstrate that our code can robustly recover a very wide range of
resistivity.
  We also illustrate the applications in modelling magnetised neutron stars,
and compare how different divergence-free handling affects the evolution of the
stars.
  Furthermore, we show that the preservation of the divergence-free condition
of magnetic field when staggered-meshed constrained transport schemes can be
significantly improved by applying elliptic cleaning.
