[utils] js_to_json: Fix bug in f55523c (#5771)

Authored by: ChillingPepper, pukkandan

yt_dlp/utils.py

@@ -3360,7 +3360,13 @@ def js_to_json(code, vars={}, *, strict=False):
                 return f'"{i}":' if v.endswith(':') else str(i)
 
         if v in vars:
-            return json.dumps(vars[v])
+            try:
+                if not strict:
+                    json.loads(vars[v])
+            except json.decoder.JSONDecodeError:
+                return json.dumps(vars[v])
+            else:
+                return vars[v]
 
         if not strict:
             return f'"{v}"'