Expected property <property_name> to be an array but instead got: instance

[jscharf]

BUG REPORT

• I have ensured that the issue isn't already reported
• I have confirmed that the issue is reproducible with the latest released version
• I have deleted the FEATURE REQUEST / CODE CHANGE section

Summary

• A warning is logged to the browser console
• Warning message is Expected property data to be an array but instead got: instance
• Possibly related to issue failed instanceOf throws error when not function #117

Expected Behavior

• A warning should not be logged to the browser console

Actual Behavior

• What happens instead of the expected behavior?
• Is something broken, or not behaving as you expected?
• Attach a screenshot or recording as appropriate.

Possible Solution

• Address issue failed instanceOf throws error when not function #117, which I think is related

Steps to Reproduce

• Include the contents of your package.json file
• Steps to reproduce:
  1. Use PropType.array to define a property
  2. Pass in an instance of an array as that property
  3. View browser console for the warning

Context

• This issue has produced many warnings in the browser console

Environment

(answer all that are applicable)

• I am using the latest released version (can check with npm ls <package-name>)
• I am using these browsers:
  • Latest Chrome
  • Latest Firefox
• My version of Node is: 8.6.0
• My version of npm is: 5.3.0
• My OS is:
• Include the contents of your package.json file