Merge branch '3' into 4

phpunit.xml.dist

@@ -1,16 +1,16 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<phpunit bootstrap="vendor/silverstripe/framework/tests/bootstrap.php" colors="true">
-    <testsuites>
-        <testsuite name="Default">
-            <directory>tests/</directory>
-        </testsuite>
-    </testsuites>
-    <filter>
-        <whitelist addUncoveredFilesFromWhitelist="true">
-            <directory suffix=".php">src/</directory>
-            <exclude>
-                <directory suffix=".php">tests/</directory>
-            </exclude>
-        </whitelist>
-    </filter>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" bootstrap="vendor/silverstripe/framework/tests/bootstrap.php" colors="true" xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.3/phpunit.xsd">
+  <coverage includeUncoveredFiles="true">
+    <include>
+      <directory suffix=".php">src/</directory>
+    </include>
+    <exclude>
+      <directory suffix=".php">tests/</directory>
+    </exclude>
+  </coverage>
+  <testsuites>
+    <testsuite name="Default">
+      <directory>tests/</directory>
+    </testsuite>
+  </testsuites>
 </phpunit>

src/DataFormatter/XMLDataFormatter.php

@@ -126,7 +126,7 @@ public function convertDataObjectWithoutHeader(DataObject $obj, $fields = null,
                 continue;
             }
             $fieldValue = $obj->obj($fieldName)?->forTemplate();
-            if (!mb_check_encoding($fieldValue, 'utf-8')) {
+            if (isset($fieldValue) && !mb_check_encoding($fieldValue, 'utf-8')) {
                 $fieldValue = "(data is badly encoded)";
             }