Some error when alert construction.

Sorry no cluster config for repro, because it's just dirty state with millions restarts and other damages.

There is code:

local ok, vshard = pcall(require, 'vshard')
if ok and vshard.router ~= nil and vshard.router.info ~= nil then
    return vshard.router.info()
end
return nil

There is error:

.rocks/share/tarantool/vshard/error.lua:321: bad argument #2 to 'format' (no value) (LuajitError, code 0x20), see tarantool/src/lua/utils.c line 679

....init.lua:1454 in func replicaset_instance_info

There is local vars for this error:

args from func is empty

local format == 
{msg="Master is not configured for replicaset %s\",
name="MISSING_MASTER",
args={"replicaset"}}

tarantool / vshard

Some error when alert construction. #474