fix: nil-guard GetChannelName, GetGuildRosterInfo, InterfaceOptions* on CoA client

PlayerNames.lua:94 - GetChannelName can return nil on the CoA-Beta client
when the active channel target is not joined; capture into a local and
fall back to empty string instead of chaining :lower() on nil.

PlayerNames.lua:344 - GetGuildRosterInfo(i) returns nil name/class on
this client (same family as the AltNames.lua fix in 1c4a7e8). Skip the
iteration when name is nil to avoid indexing channels.GUILD[nil] and
passing nil into AddPlayer.

Chatter.lua:204 OpenConfig and Chatter.lua:21 inline func - the Blizzard
InterfaceOptionsFrame globals are absent on CoA-Beta, so calling
IsResizable() or InterfaceOptionsFrame_OpenToCategory() throws. Guard
both call sites and fall back to opening the standalone AceConfigDialog
window.

ChatScroll.lua:53 - InterfaceOptionsSocialPanelChatMouseScroll_SetScrolling
is also missing on this client; only hook it when the global exists,
otherwise AceHook errors out at OnInitialize.

Chatter.lua

@@ -19,9 +19,14 @@ local options = {
 					name = L["Standalone Config"],
 					desc = L["Open a standalone config window. You might consider installing |cffffff00BetterBlizzOptions|r to make the Blizzard UI options panel resizable."],
 					func = function()
-						InterfaceOptionsFrame:Hide()
-						AceConfigDialog:SetDefaultSize("Chatter", 500, 550)
-						AceConfigDialog:Open("Chatter")
+						if InterfaceOptionsFrame and InterfaceOptionsFrame_OpenToCategory then
+							InterfaceOptionsFrame:Hide()
+							AceConfigDialog:SetDefaultSize("Chatter", 500, 550)
+							AceConfigDialog:Open("Chatter")
+						else
+							AceConfigDialog:SetDefaultSize("Chatter", 500, 550)
+							AceConfigDialog:Open("Chatter")
+						end
 					end
 				}
 			}
@@ -202,15 +207,19 @@ function Chatter:FCF_OpenTemporaryWindow(chatType, chatTarget, sourceChatFrame,
 end
 
 function Chatter:OpenConfig(input)
-	if input == "config" or not InterfaceOptionsFrame:IsResizable() then
-		options.args.defaultArgs.guiHidden = true
-		InterfaceOptionsFrame:Hide()
-		AceConfigDialog:SetDefaultSize("Chatter", 500, 550)
-		AceConfigDialog:Open("Chatter")
+	if InterfaceOptionsFrame and InterfaceOptionsFrame_OpenToCategory then
+		if input == "config" or not InterfaceOptionsFrame:IsResizable() then
+			options.args.defaultArgs.guiHidden = true
+			InterfaceOptionsFrame:Hide()
+			AceConfigDialog:SetDefaultSize("Chatter", 500, 550)
+			AceConfigDialog:Open("Chatter")
+		else
+			InterfaceOptionsFrame_OpenToCategory(Chatter.lastConfig)
+			options.args.defaultArgs.guiHidden = false
+			InterfaceOptionsFrame_OpenToCategory(optFrame)
+		end
 	else
-		InterfaceOptionsFrame_OpenToCategory(Chatter.lastConfig)
-		options.args.defaultArgs.guiHidden = false
-		InterfaceOptionsFrame_OpenToCategory(optFrame)
+		LibStub("AceConfigDialog-3.0"):Open("Chatter")
 	end
 end