fix: guard nil note/rank from GetGuildRosterInfo on CoA client

GetGuildRosterInfo returns nil for the public-note and rank fields on the
CoA Beta client, so ScanGuildNotes crashed at AltNames.lua:331 on
strlower(note). Guard note and rank the same way upstream already guards
name, and skip the alt-note fallback entirely when there is no note.

Modules/AltNames.lua

@@ -328,7 +328,7 @@ function mod:ScanGuildNotes()
 	for i=1,GetNumGuildMembers(true) do
 		local name, rank, rankIndex, level, class, zone, note, officernote, online, status = GetGuildRosterInfo(i);
 		local success
-		for word in gmatch(strlower(note), "[%a\128-\255]+") do
+		for word in gmatch(strlower(note or ""), "[%a\128-\255]+") do
 			if names[word] then
 				GUILDNOTES[name] = names[word]
 				success = true
@@ -336,9 +336,9 @@ function mod:ScanGuildNotes()
 				break
 			end
 		end
-		if not success and mod.db.profile.altNotesFallback and note~="" then
+		if not success and mod.db.profile.altNotesFallback and note and note~="" then
 			-- #3:  no joy? then if this is an 'alt' rank, use the entire note
-			rank=strlower(rank)
+			rank=strlower(rank or "")
 			if strfind(rank, "alt") or
 				strfind(rank, L["alt2"]) or
 				strfind(rank, L["alt3"]) then