fix output_dir make gen-main error

nhentai/utils.py

@@ -100,7 +100,11 @@ def generate_main_html(output_dir='.'):
                 </div>\n\
             </div>\n'
     
-    os.chdir(output_dir) # switch to given dir
+    if output_dir == '':
+        os.chdir('.')
+    else:
+        os.chdir(output_dir) 
+    # switch to given dir
     doujinshi_dirs = next(os.walk('.'))[1] 
     # https://stackoverflow.com/questions/141291/how-to-list-only-top-level-directories-in-python
 

nhentai/viewer/scripts.js

@@ -50,6 +50,7 @@ document.onkeypress = event => {
         case 'a':
             changePage(currentPage - 1);
             break;
+        // Return to previous page
         case 'q':
             window.history.go(-1);
             break;