bgpd: Fix crash when rd has no data

There exists a state where we may have a rd node but no individual
evpn prefix nodes in the two level table:

(gdb) bt
    at bgpd/bgp_evpn_vty.c:1190
    filter=FILTER_RELAXED) at lib/command.c:1060
    at lib/command.c:1119
    vtysh=vtysh@entry=0) at lib/command.c:1273
(gdb) f 5
    at bgpd/bgp_evpn_vty.c:1190
1190    bgpd/bgp_evpn_vty.c: No such file or directory.
(gdb) p buf
$1 = "[2]:[0]:[48]:[00:00:00:00:00:00]", '\000' <repeats 240 times>...
(gdb) p json_nroute
$2 = (json_object *) 0x0
(gdb) p rd_header
$3 = 1
(gdb) p buf
$4 = "[2]:[0]:[48]:[00:00:00:00:00:00]", '\000' <repeats 240 times>...
(gdb)

I'm not entirely sure that this is not a `different` problem in that the
rd node should have been removed.  But I think preventing the crash
in a show command is probably the right thing to do here.

Fixes: #4501
Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>

0 files changed, 0 insertions, 0 deletions