Creator scheduled Deluge repeatedly failing - unable to replicate error manually

Creator scheduled Deluge repeatedly failing - unable to replicate error manually

I have a scheduled workflow that runs every morning to bring in data from another system and check for updates. I'm seeing in the error logs that it fails :

Error details:
      Error in executing SYSTEMNAME Update
            Error at line : 23, Invalid collection string

Line 23 is
  1. varData = varRawData.getJSON("employees");

However when I run the code manually it works, no problem. and when I write info varData it returns the information I would expect.

How else can I work out what the problem is if I can not replicate the error ?