Apply patch from Issue #3365895, Comment #9

Closes #3365895

core/modules/migrate/src/Plugin/migrate/process/SubProcess.php

@@ -3,6 +3,7 @@
 namespace Drupal\migrate\Plugin\migrate\process;
 
 use Drupal\migrate\MigrateException;
+use Drupal\migrate\MigrateSkipRowException;
 use Drupal\migrate\ProcessPluginBase;
 use Drupal\migrate\MigrateExecutableInterface;
 use Drupal\migrate\Row;
@@ -208,7 +209,12 @@ public function transform($value, MigrateExecutableInterface $migrate_executable
           throw new MigrateException(sprintf("Input array should hold elements of type array, instead element was of type '%s'", gettype($new_value)));
         }
         $new_row = new Row($new_value + $source);
-        $migrate_executable->processRow($new_row, $this->configuration['process']);
+        try {
+          $migrate_executable->processRow($new_row, $this->configuration['process']);
+        }
+        catch (MigrateSkipRowException $e) {
+          continue;
+        }
         $destination = $new_row->getDestination();
         if (array_key_exists('key', $this->configuration)) {
           $key = $this->transformKey($key, $migrate_executable, $new_row);