Uninstalling or upgrading the eclipse-support plugin results in an error similar to the following one
[sample]> griffon uninstall-plugin eclipse-support
Welcome to Griffon 1.2.0 - http:Licensed under Apache Standard License 2.0
Griffon home is set to: /usr/local/griffon
Base Directory: /private/tmp/sample
Running script /usr/local/griffon/scripts/UninstallPlugin_.groovy
Dependencies resolved in 507ms.
Environment set to development
Resolving framework plugin dependencies ...
Framework plugin dependencies resolved in 1140 ms.
Resolving plugin dependencies ...
Plugin dependencies resolved in 826 ms.
[delete] Deleting directory /Users/aalmiray/.griffon/1.2.0/projects/sample/plugins/eclipse-support-0.6.2
An error occured uninstalling the plugin [eclipse-support]: Cannot invoke method exists() on null object
PD: there's a typo in the error message too.