Using 6.5.1 I have the current version (1.1.0) installed. I have something (not 100% sure) in mind I had to delete my browser cache after upgrading to get rid of this error message. Probably something you can try and provide feedback if that solved your issue (just to help other if they running into the same issue)
Does the "Punchcard Gallery" dashboard also not working or this is an issue only related to a custom search ?
Punchcard Gallery URL: YOURSPLUNKURL/en-US/app/punchcard_app/gallery
If it's only related to your custom search just post some search details here.
If this issue is app related I recommend to open a support ticket at Splunk (as this app is from Splunk they should be able to provide some help)
Had a similar issue with 6.4.3 and this app. Rollback the app version to Version 1.0.0 and everything worked fine for me again. Seems to be an issue with the current version or the current version only works with Splunk 6.5 (didn't had the time to test). Hope that helps