fixed few errors

Author: Malmahrouqi3

src/simulation/m_riemann_solvers.fpp

@@ -329,7 +329,7 @@ contains
         real(wp) :: alpha_L_sum, alpha_R_sum
         real(wp) :: zcoef, pcorr !< low Mach number correction
 
-        type(riemann_states) :: c_fast, pres_mag
+        type(riemann_states) :: c_fast, pres_mag, vel
         type(riemann_states_vec3) :: B
 
         type(riemann_states) :: Ga ! Gamma (Lorentz factor)
@@ -1209,6 +1209,8 @@ contains
 
         integer :: i, j, k, l, q !< Generic loop iterators
         integer :: idx1, idxi
+        type(riemann_states) :: c_fast, vel
+        integer :: loop_end
 
         ! Populating the buffers of the left and right Riemann problem
         ! states variables, based on the choice of boundary conditions