Bugfix/xml merger do not throw exception of missing xml (#88)

* Issue XML Report Merger
- continue if xml report file did not exist
- print task warning message

src/Merger/XmlReportMergerTask.php

@@ -92,8 +92,9 @@ public function run(): void
             $this->printTaskInfo("Processing $src");
 
             $srcXml = new DOMDocument();
-            if (!file_exists($src)) {
-                throw new TaskException($this, "XML file $src does not exist");
+            if (!file_exists($src) || !is_readable($src)) {
+                $this->printTaskWarning('File did not exists or is not readable: ' . $src);
+                continue;
             }
             $loaded = $srcXml->load($src);
             if (!$loaded) {

tests/Merger/XmlReportMergerTaskTest.php

@@ -16,6 +16,8 @@ public function testMergeReports(): void
         $task->setLogger(new Logger(new NullOutput()));
         $task->from(TEST_PATH . '/fixtures/result1.xml')
             ->from(TEST_PATH . '/fixtures/result2.xml')
+            // This report did not exists and we should not throw an exception
+            ->from(TEST_PATH . '/fixtures/result3.xml')
             ->into(TEST_PATH . '/result/merged.xml')
             ->run();