Improve logic handle auto-allocation of ports for a server

app/Exceptions/Service/Allocation/AutoAllocationNotEnabledException.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace Pterodactyl\Exceptions\Service\Allocation;
+
+use Pterodactyl\Exceptions\DisplayException;
+
+class AutoAllocationNotEnabledException extends DisplayException
+{
+    /**
+     * AutoAllocationNotEnabledException constructor.
+     */
+    public function __construct()
+    {
+        parent::__construct(
+            'Server auto-allocation is not enabled for this instance.'
+        );
+    }
+}

app/Exceptions/Service/Allocation/NoAutoAllocationSpaceAvailableException.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace Pterodactyl\Exceptions\Service\Allocation;
+
+use Pterodactyl\Exceptions\DisplayException;
+
+class NoAutoAllocationSpaceAvailableException extends DisplayException
+{
+    /**
+     * NoAutoAllocationSpaceAvailableException constructor.
+     */
+    public function __construct()
+    {
+        parent::__construct(
+            'Cannot assign additional allocation: no more space available on node.'
+        );
+    }
+}