Handle DB nullability

Libraries/SPTarkov.Server.Core/Exceptions/Database/DatabaseNullException.cs

@@ -0,0 +1,10 @@
+namespace SPTarkov.Server.Core.Exceptions.Database;
+
+public class DatabaseNullException : Exception
+{
+    public DatabaseNullException(string message)
+        : base(message) { }
+
+    public DatabaseNullException(string message, Exception innerException)
+        : base(message, innerException) { }
+}

Libraries/SPTarkov.Server.Core/Exceptions/Database/DatabaseTablesAlreadySetException.cs

@@ -0,0 +1,10 @@
+namespace SPTarkov.Server.Core.Exceptions.Database;
+
+internal class DatabaseTablesAlreadySetException : Exception
+{
+    public DatabaseTablesAlreadySetException(string message)
+        : base(message) { }
+
+    public DatabaseTablesAlreadySetException(string message, Exception innerException)
+        : base(message, innerException) { }
+}