Draft: quick patch for surfacing/recording migrate_lookup stub row skips

Closes #3447713

core/modules/migrate/src/MigrateStub.php

@@ -109,7 +109,33 @@ protected function doCreateStub(MigrationInterface $migration, array $source_ids
     $id_map = $migration->getIdMap();
     $migrate_executable = new MigrateExecutable($migration);
     $row = new Row($source_ids + $migration->getSourceConfiguration(), $migration->getSourcePlugin()->getIds(), TRUE);
-    $migrate_executable->processRow($row, $process);
+
+    try {
+      $migrate_executable->processRow($row, $process);
+    }
+    catch (MigrateSkipRowException $e) {
+      if ($e->getSaveToMap()) {
+        $id_map->saveIdMapping($row, [], MigrateIdMapInterface::STATUS_IGNORED);
+      }
+
+      if ($message = trim($e->getMessage())) {
+        // Figure out the destination key that failed:
+        $current_destination_key = [];
+
+        foreach ($process as $destination_key => $destination_value) {
+          if (!array_key_exists($destination_key, $row->getDestination())) {
+            $current_destination_key = $destination_key;
+            break;
+          }
+        }
+
+        $msg = sprintf("%s:%s: %s", $migration->getPluginId(), $current_destination_key, $message);
+        $id_map->saveMessage($row->getSourceIdValues(), $msg, MigrationInterface::MESSAGE_INFORMATIONAL);
+      }
+
+      return FALSE;
+    }
+
     foreach ($default_values as $key => $value) {
       $row->setDestinationProperty($key, $value);
     }