Add missing aux_logic declaration. Force compliance with optional argument.

diff --git a/src/ext/lclist.f90 b/src/ext/lclist.f90
index ef54e11..0d21b55 100644
--- a/src/ext/lclist.f90
+++ b/src/ext/lclist.f90
@@ -405,6 +405,7 @@ contains
     integer                                           :: iat, iT, sgn
     double precision                                  :: Rc, Rc2, dist2
     double precision, dimension(3)                    :: coo2, cart
+    logical                                           :: aux_logic = .True.

     if (.not. isInit) then
        write(0,*) "Error: module not initialized in `nbdist'."
@@ -480,7 +481,11 @@ contains

     do inb = 1, nnb2
        iat = nblist(inb)
-       if ( present(itype) .and. (atomType(iat) /= itype)) cycle
+       ! BCM: Make the logic comply with optional argument existence:
+       !if ( present(itype) .and. (atomType(iat) /= itype)) cycle
+       if ( present(itype)) then
+          if ( (atomType(iat) /= itype)) cycle
+       end if
        ! in home unit cell:
        cart(1:3) = cooLatt(1:3,iat) - cooLatt(1:3,iatom)
        cart(1:3) = matmul(latticeVec, cart(1:3))