getGlobal being called on 'null'

[rehanift]

[9/Jun/2012:09:37:34 GMT-0700] Piston "Error: [TypeError: Cannot call method 'getGlobal' of undefined]
"

/home/rehanift/src/engine.js-examples/craigslist-job-scraper/node_modules/engine.js/lib/engine/cylinder.js:78
      task_id: current_task.task_id,
                           ^
TypeError: Cannot read property 'task_id' of null
    at [object Object].<anonymous> (/home/rehanift/src/engine.js-examples/craigslist-job-scraper/node_modules/engine.js/lib/engine/cylinder.js:78:28)
    at [object Object].emit (events.js:70:17)
    at [object Object].<anonymous> (/home/rehanift/src/engine.js-examples/craigslist-job-scraper/node_modules/engine.js/lib/engine/cylinder/piston_process_manager.js:26:13)
    at [object Object].emit (events.js:70:17)
    at [object Object].<anonymous> (/home/rehanift/src/engine.js-examples/craigslist-job-scraper/node_modules/engine.js/lib/engine/cylinder/piston_process_watcher.js:26:10)
    at [object Object].emit (events.js:70:17)
    at ChildProcess.<anonymous> (/home/rehanift/src/engine.js-examples/craigslist-job-scraper/node_modules/engine.js/lib/engine/cylinder/piston_process.js:22:20)
    at ChildProcess.emit (events.js:70:17)
    at maybeExit (child_process.js:362:16)
    at Process.onexit (child_process.js:398:5)