reproducible segfault in master branch

You'll get a better error message/behavior now using:

But ultimately, you likely want to do something like this patch:

--- known-hosts-with-dns.bro.orig 2018-08-15 11:07:41.000000000 -0500
+++ known-hosts-with-dns.bro 2018-08-15 10:44:03.000000000 -0500
@@ -113,7 +113,7 @@
  for (ip in r$result as addr_set){
  when ( local res = Broker::get(Known::host_store$store,ip)){

-     if(res?$result){
+     if(res$status == Broker::SUCCESS){
  @if ( ! Cluster::is_enabled() )
  Known::hosts[ip] = fmt("%s",res$result as string);

As for why some keys no longer exist in those lookups immediately
after retrieving the full key set: my guess is they simply expired
between those two points in time, but I didn't dig into it. The main
point would be to never assume the Broker::get() call succeeds, which
was likely your intent, except "res?$result" is always true (another
form of checking the data exists would be "res$result?$data").

- Jon

Excellent, thanks Jon!