Validate player identifier in DeleteCharacter function

[core]/esx_multicharacter/server/modules/database.lua

@@ -73,7 +73,14 @@ MySQL.ready(function()
 end)
 
 function Database:DeleteCharacter(source, charid)
-    local identifier = ("%s%s:%s"):format(Server.prefix, charid, ESX.GetIdentifier(source))
+    local playerIdentifier = ESX.GetIdentifier(source)
+    if not playerIdentifier then
+        local name = GetPlayerName(source) or "Unknown"
+        print(("[^1ERROR^7] Failed to delete character for ^5%s %s^7: invalid or missing identifier"):format(name, source))
+        return
+    end
+    
+    local identifier = ("%s%s:%s"):format(Server.prefix, charid, playerIdentifier)
     local query = "DELETE FROM `%s` WHERE %s = ?"
     local queries = {}
     local count = 0
@@ -141,4 +148,4 @@ function Database:DisableSlot(identifier, slot)
     return updated > 0
 end
 
-Database:GetConnection()
+Database:GetConnection()