executeScript_sandbox and getting ES5 to work

I’ve converted .includes to .indexof, but now I need some help with this simple bit of code. I’m changing my code to the sandbox (version ES5) due to other errors ('Trusted Type' assignment error with Google Form - #2 by PT7)

With the sandbox I’m getting this error:
[error] Line 164: Unterminated regular expression (1:17)

var time = parseFloat(${!runtime});
var Update = false;
if (time - ${lastRunningTime} > 600) Update=true;
return Update

The error is something to do with template literals.

Any suggestions greatly appreciated.

Solved it. Embarrassing, but true… the first line was a comment (missing in my example above)…
/ ES5
it should be…
// ES5