fix panic when meta is null

Author: georgeji

apisix/discovery/consul/init.lua

@@ -517,6 +517,9 @@ function _M.connect(premature, consul_server, retry_delay)
                     end
 
                     local svc_address, svc_port, metadata = service.Address, service.Port, service.Meta
+                    if type(metadata) ~= "table" then
+                       metadata = nil
+                    end
                     -- Handle nil or 0 port case - default to 80 for HTTP services
                     if not svc_port or svc_port == 0 then
                         svc_port = 80