Issue #3270564 by quietone: Handle NULL for data blob in User source plugin

(cherry picked from commit c8b2c112)

core/modules/user/src/Plugin/migrate/source/d7/User.php

@@ -76,7 +76,7 @@ public function prepareRow(Row $row) {
       ->fetchCol();
     $row->setSourceProperty('roles', $roles);
 
-    $row->setSourceProperty('data', unserialize($row->getSourceProperty('data')));
+    $row->setSourceProperty('data', unserialize($row->getSourceProperty('data') ?? ''));
 
     // If this entity was translated using Entity Translation, we need to get
     // its source language to get the field values in the right language.

core/modules/user/tests/src/Kernel/Plugin/migrate/source/d7/UserTest.php

@@ -54,6 +54,18 @@ public function providerSource() {
         'field_file_display' => 1,
         'field_file_description' => 'None',
       ],
+      [
+        'entity_type' => 'user',
+        'bundle' => 'user',
+        'deleted' => 0,
+        'entity_id' => 3,
+        'revision_id' => NULL,
+        'language' => 'und',
+        'delta' => 0,
+        'field_file_fid' => 42,
+        'field_file_display' => 1,
+        'field_file_description' => 'None',
+      ],
     ];
     $tests[0]['source_data']['role'] = [
       [
@@ -81,12 +93,34 @@ public function providerSource() {
         'init' => 'odo@local.host',
         'data' => 'a:1:{s:7:"contact";i:1;}',
       ],
+      [
+        'uid' => '3',
+        'name' => 'foo',
+        'pass' => 'password',
+        'mail' => 'foo@local.host',
+        'theme' => '',
+        'signature' => '',
+        'signature_format' => 'filtered_html',
+        'created' => '1647752102',
+        'access' => '0',
+        'login' => '0',
+        'status' => '1',
+        'timezone' => 'America/Chicago',
+        'language' => '',
+        'picture' => '0',
+        'init' => 'foo@local.host',
+        'data' => NULL,
+      ],
     ];
     $tests[0]['source_data']['users_roles'] = [
       [
         'uid' => 2,
         'rid' => 2,
       ],
+      [
+        'uid' => 3,
+        'rid' => 2,
+      ],
     ];
 
     // The expected results.
@@ -118,6 +152,31 @@ public function providerSource() {
           ],
         ],
       ],
+      [
+        'uid' => '3',
+        'name' => 'foo',
+        'pass' => 'password',
+        'mail' => 'foo@local.host',
+        'signature' => '',
+        'signature_format' => 'filtered_html',
+        'created' => '1647752102',
+        'access' => '0',
+        'login' => '0',
+        'status' => '1',
+        'timezone' => 'America/Chicago',
+        'language' => '',
+        'picture' => '0',
+        'init' => 'foo@local.host',
+        'roles' => [2],
+        'data' => FALSE,
+        'field_file' => [
+          [
+            'fid' => 42,
+            'display' => 1,
+            'description' => 'None',
+          ],
+        ],
+      ],
     ];
 
     return $tests;