Steps to reproduce:

1. Create script item type
2. Set 'some-api-variable' parameter:

request.AddHeader('x-api-key: '+params.some-api-parameter);

Result:

Cannot execute script: ReferenceError: identifier 'api' undefined
        at [anon] (duktape.c:81729) internal
        at [anon] (function:7) preventsyield

Expected in documentation:

The names of variables, called identifiers, conform to certain rules. A JavaScript identifier must start with a letter, underscore ( _ ), or dollar sign ( $ ). Subsequent characters can also be digits ( 0 – 9 ).

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Grammar_and_types