You could also install the addon
Zgoo and append the following code to its Startup.lua file.
Lua Code:
ZO_PreHook(CENTER_SCREEN_ANNOUNCE, "CallExpiringCallback", function(self, announcementLine)
if not announcementLine then
d("announcementLine is missing")
else if not announcementLine:GetMessageParams() then
Zgoo:Main(nil, 1, announcementLine)
end
end)
This should either print a message in chat if the announcementLine is nil, or open an inspector window for the announcementLine, which could contain a clue as to where the malformed object is coming from.