Fix deprecation for symfony/config 4.2

Author: mhujer

README.md

@@ -55,6 +55,9 @@ Author
 Changelog
 ----------
 
+### 1.3 (2018-XX-XX)
+- Symfony 4.2 compatibility
+
 ### 1.2 (2018-11-16)
 - PHP 7.3 compatibility
 

composer.json

@@ -18,12 +18,12 @@
 	],
 	"require": {
 		"php": "~7.1",
-		"symfony/config": "^3.3|^4.0",
-		"symfony/dependency-injection": "^3.3|^4.0",
-		"symfony/event-dispatcher": "^3.3|^4.0",
-		"symfony/expression-language": "^3.3|^4.0",
-		"symfony/http-foundation": "^3.3|^4.0",
-		"symfony/http-kernel": "^3.3|^4.0"
+		"symfony/config": "^4.2",
+		"symfony/dependency-injection": "^4.2",
+		"symfony/event-dispatcher": "^4.2",
+		"symfony/expression-language": "^4.2",
+		"symfony/http-foundation": "^4.2",
+		"symfony/http-kernel": "^4.2"
 	},
 	"require-dev": {
 		"consistence/coding-standard": "3.5",

src/DependencyInjection/Configuration.php

@@ -22,8 +22,8 @@ public function __construct(
 
 	public function getConfigTreeBuilder(): TreeBuilder
 	{
-		$treeBuilder = new TreeBuilder();
-		$rootNode = $treeBuilder->root('java_script_error_handler');
+		$treeBuilder = new TreeBuilder('java_script_error_handler');
+		$rootNode = $treeBuilder->getRootNode();
 
 		// @codingStandardsIgnoreStart tree is indented for better readability
 		$rootNode