Tagging plugin issues error/warning

After installing the (ECM) tagging plugin and adding a tags field to a document type, I see the following messages on the console:

ERROR http-bio-8080-exec-7 [PluginFactory.createPlugin:106] No plugin classname configured, please set plugin configuration parameter plugin.class
Failed to instantiate plugin class 'null' for wicket id 'null' in plugin 'home.cluster.cms-static.plugin.navigator.cluster.cms-browser.plugin.navigator' (JcrPluginConfig:/hippo:configuration/hippo:frontend/cms/cms-browser/navigator)

WARN http-bio-8080-exec-5 [ObservableRegistry.addObserver:135] Same observer [TagSuggestPlugin [Component id = service.render]] registered multiple times

This may be an ECM tagging forge plugin problem...?