Numerical problem in "deptht"

I think in line 22494 either the "lt" must be "le", or another check on "i" not becoming negative must be added.

#1  0x0000555556503953 in deptht (dist=20000.000000000109, radt=0)
    at /home/rulrich/work/corsika/corsika/modules/conex/src/conex_sub.F:22492
22492           s=s+depth0(R1,R2,a,i)
(gdb) print i
$4 = -8
(gdb) list
22487         i=mxatm
22488         do
22489           R2=max(eatm(i)+Rt, a)
22490           xi=sqrt((R2-a)*(R2+a))
22491           if (xi.le.xx) goto 10
22492           s=s+depth0(R1,R2,a,i)
22493           R1=R2
22494           if (eatm(i).lt.a-RadGrd) goto 10
22495           i=i-1
22496         enddo
(gdb) print mxatm
$5 = 5
(gdb) print eatm
$6 = (0, 4000, 10000, 40000, 100000, 100000)
(gdb) print a
$7 = 0
(gdb) print RadGrd