nodejs integration error

I found the nodejs integration example page, cloned it down and followed the instructions to generate references. I'm getting thrown an error which I'll paste below:

```
Config detected:
COMMAND | Executing core for `reference`
clean | backstop_data/second-project/bitmaps_reference was cleaned.
createBitmaps | Selcted 2 of 2 scenarios.
COMMAND | Command `reference` ended with an error
COMMAND | TypeError: Converting circular structure to JSON
at JSON.stringify ()
at writeReferenceCreateConfig (/Users/jennynorthcott/developer_projects/BackstopJS/examples/nodeIntegration/node_modules/backstopjs/core/util/createBitmaps.js:65:58)
at module.exports (/Users/jennynorthcott/developer_projects/BackstopJS/examples/nodeIntegration/node_modules/backstopjs/core/util/createBitmaps.js:139:10)
at /Users/jennynorthcott/developer_projects/BackstopJS/examples/nodeIntegration/node_modules/backstopjs/core/command/reference.js:19:14
(node:13681) UnhandledPromiseRejectionWarning: TypeError: Converting circular structure to JSON
at JSON.stringify ()
at writeReferenceCreateConfig (/Users/jennynorthcott/developer_projects/BackstopJS/examples/nodeIntegration/node_modules/backstopjs/core/util/createBitmaps.js:65:58)
at module.exports (/Users/jennynorthcott/developer_projects/BackstopJS/examples/nodeIntegration/node_modules/backstopjs/core/util/createBitmaps.js:139:10)
at /Users/jennynorthcott/developer_projects/BackstopJS/examples/nodeIntegration/node_modules/backstopjs/core/command/reference.js:19:14
(node:13681) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
(node:13681) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
```

I'm wondering if there's a quick fix?