Bug fix: the electric field calculation for ionization had a bug if e…

…xternal electric field and grid electric field co-exist in the quasi-cylindrical geometry. This commit fixes this bug. (ECP-WarpX#4094)

Source/Particles/ElementaryProcess/Ionization.H

@@ -96,13 +96,13 @@ struct IonizationFilterFunc
 
             amrex::ParticleReal ex = 0._rt, ey = 0._rt, ez = 0._rt;
             amrex::ParticleReal bx = 0._rt, by = 0._rt, bz = 0._rt;
-            m_get_externalEB(i, ex, ey, ez, bx, by, bz);
 
             doGatherShapeN(xp, yp, zp, ex, ey, ez, bx, by, bz,
                            m_ex_arr, m_ey_arr, m_ez_arr, m_bx_arr, m_by_arr, m_bz_arr,
                            m_ex_type, m_ey_type, m_ez_type, m_bx_type, m_by_type, m_bz_type,
                            m_dx_arr, m_xyzmin_arr, m_lo, m_n_rz_azimuthal_modes,
                            m_nox, m_galerkin_interpolation);
+            m_get_externalEB(i, ex, ey, ez, bx, by, bz);
 
             // Compute electric field amplitude in the particle's frame of
             // reference (particularly important when in boosted frame).