bugfix: move sidebyside accessor outside of options check

src/js/easymde.js

@@ -332,9 +332,10 @@ function toggleFullScreen(editor) {
         document.body.style.overflow = saved_overflow;
     }
 
+    var sidebyside = cm.getWrapperElement().nextSibling;
+
     // Hide side by side if needed, retain current state if sideBySideFullscreen is disabled
     if (editor.options.sideBySideFullscreen !== false) {
-        var sidebyside = cm.getWrapperElement().nextSibling;
         if (/editor-preview-active-side/.test(sidebyside.className))
             toggleSideBySide(editor);
     }