Report javascript parse errors

[mrcnski]

I was running a script:

alice: js-script ./0004-configure-relay.js with "" return is 0 within 600 secs

with some code like this:

const calls = [
  api.tx.configuration.setCoretimeCores({ new: 2 }),
  api.tx.coretime.assignCore(0, 20, [[ { task: 100 }, 57600 ]], null)
  api.tx.coretime.assignCore(1, 20, [[ { task: 1005 }, 57600 ]], null)
];

and I was getting this error (nothing else):

│ 12/19/2023, 12:20:52 PM      │  ❌ alice: js-script ./0004-configure-relay.js with "" return is 0 within 600 secs (37ms)           │

Can you see the problem? It took me hours to notice it. I thought it was a problem with assignCore!

We should report back if there is a syntax error in the script, instead of failing silently.