Fix potential bug where using !unset on a variable would result in a crash

app/Engine/Cfnpp/Compiler.php

@@ -202,7 +202,13 @@ class Compiler implements \App\Engine\ICompile
 		foreach ($variables_ordered as $variable)
 		{
 			$this->runFunctions($variables_raw[$variable]);
-			$options->setVariable($variable, Node::toPhp($variables_node->getChildByName($variable)));
+			$variable_node = $variables_node->getChildByName($variable);
+			// By all accounts this _should_ still exist, but this accounts for the
+			// case where, say, someone had used !unset on a variable for some reason.
+			if (isset($variable_node))
+			{
+				$options->setVariable($variable, Node::toPhp($variable_node));
+			}
 		}
 	}