if Priestley is rendered but not visible, it will throw a data error

[davelandry]

Expected Behavior

Priestley visualizations, just like others, should be able to be rendered when not visible on the page.

Current Behavior

When rendering a Priestley visualization on a page, and using the default "detectVisible" behavior to only draw it when it is visible, an error is thrown.

Steps to Reproduce (for bugs)

1. Call .render() on a Priestley not visible in the viewport while having detectVisible set to true (default).

Your Environment

• Browser Name: Chrome
• Operating System and Version: macOS Sierra