Inserting Custom Code

Hi ,
inserting JS-code into Helix Ultimate template via template options , does not work.

Whe I try to insert JS before /head I get this strange error and success notification mix. But the code does not appear in source code finally .

Further experienced massive loading time right after those JS trials.

https://prnt.sc/9r8KeqXqcwT2

Generally concerned about this behavior and error notification on a new website. Same happens with other JS snippets.

Please advise,

Thanks

Jag