Merge forwardport of magento/magento2#12859 to 2.3-develop branch

Applied pull request patch https://github.com/magento/magento2/pull/12859.patch (created by @pmclain) based on commit(s):
  1. ab5e153

Author: magento-engcom-team

app/code/Magento/Config/Model/Config/Structure/Reader.php

@@ -124,14 +124,18 @@ protected function _readFiles($fileList)
      * Processing nodes of the document before merging
      *
      * @param string $content
+     * @throws \Magento\Framework\Config\Dom\ValidationException
      * @return string
      */
     protected function processingDocument($content)
     {
         $object = new DataObject();
         $document = new \DOMDocument();
-
-        $document->loadXML($content);
+        try {
+            $document->loadXML($content);
+        } catch (\Exception $e) {
+            throw new \Magento\Framework\Config\Dom\ValidationException($e->getMessage());
+        }
         $this->compiler->compile($document->documentElement, $object, $object);
 
         return $document->saveXML();

app/code/Magento/Config/Test/Unit/Model/Config/Structure/ReaderTest.php

@@ -100,4 +100,24 @@ public function testReadSuccessNotValidatedCase()
 
         $this->assertEquals($expectedResult, $this->reader->read());
     }
+
+    /**
+     * Test the execution with the Validation exception of the 'read' method
+     * 
+     * @expectedException \Magento\Framework\Exception\LocalizedException
+     * @expectedExceptionMessage Invalid XML in file file:
+     */
+    public function testReadWithValidationException()
+    {
+        $content = '<config><item name="test1"></item><wrong></config>';
+        $expectedResult = ['result_data'];
+        $fileList = ['file' => $content];
+
+        $this->fileResolverMock->expects($this->once())
+            ->method('get')
+            ->with('system.xml', 'global')
+            ->willReturn($fileList);
+        
+        $this->assertEquals($expectedResult, $this->reader->read());
+    }
 }