fix: do not require lessons definition in other languages

user/plugins/m3-p2/m3-p2.php

@@ -298,11 +298,13 @@ class M3P2Plugin extends Plugin
 
         $target_pages = array_filter($pages->instances(), function (Page $p) use ($lesson_slug) {
 
+
             $page_config = $p->header();
             if ( ! isset($page_config->lessons) || empty($page_config->lessons)) {
                 return false;
             }
 
+
             foreach ($page_config->lessons as $lesson) {
 
                 if ( ! isset($lesson['slug'])) {
@@ -333,11 +335,11 @@ class M3P2Plugin extends Plugin
             };
 
             $mar = array_filter($ha->lessons, $fdp);
-            assert($mar && !empty($mar), "No lesson found for $lesson_slug in page ".$a->url());
+            assert($mar && ! empty($mar), "No lesson found for $lesson_slug in page ".$a->url());
             $ma = array_shift($mar);
 
             $mbr = array_filter($hb->lessons, $fdp);
-            assert($mbr && !empty($mbr), "No lesson found for $lesson_slug in page ".$b->url());
+            assert($mbr && ! empty($mbr), "No lesson found for $lesson_slug in page ".$b->url());
             $mb = array_shift($mbr);
 
             if ($ma && isset($ma['order'])) {
@@ -350,23 +352,25 @@ class M3P2Plugin extends Plugin
             return $la - $lb;
         });
 
+
         if (empty($target_pages)) {
-            return;
+            return false;
         }
 
         $current_lesson_lang = $target_pages[0]->language();
-        $current_lesson_name = "";
+        $current_lesson_name = "";  // unused for now
         $current_found = false;
         $previous_found = false;
         $next_found = false;
         $previous_lesson_slug = "";
-        $previous_lesson_name = "";
+        $previous_lesson_name = "";  // unused for now
         $next_lesson_slug = "";
         $other_lessons = [];  // of slug => ['name' => …, 'slug' => …]
         foreach ($target_pages as $target_page) {
             $page_config = $target_page->header();
             if ( ! isset($page_config->lessons) || empty($page_config->lessons)) {
-                return false;
+                // Unless we edit the code above, this _should_ never happen.
+                die("Some pages are lacking a lessons configuration.");
             }
             foreach ($page_config->lessons as $page_lesson) {
                 if ( ! isset($page_lesson['slug'])) {
@@ -415,7 +419,7 @@ class M3P2Plugin extends Plugin
 
                 $page_config = $translated_target_page->header();
                 if ( ! isset($page_config->lessons) || empty($page_config->lessons)) {
-                    return false;
+                    continue;  // other languages may not define lessons
                 }
 
                 foreach ($page_config->lessons as $lesson) {