Fix crash when escaping command_documentation

custom/4coder_docs.cpp

@@ -195,9 +195,11 @@ CUSTOM_DOC("Prompts the user to select a command then loads a doc buffer for tha
         Scratch_Block scratch(app);
         Doc_Cluster *docs = doc_commands(scratch);
         Doc_Page *page = get_doc_page_from_user(app, docs, "Doc Page:");
+        if (page != 0){
             Buffer_ID buffer = render_doc_page(app, page);
             view_set_buffer(app, view, buffer, 0);
         }
+    }
 }
 
 // BOTTOM