I am logged in a Admin and running in to this error every time I try to preview or save to our custom Admin Asset Search Rail (Tools>General>Search forms). Unfortunately, I cannot find information or help specific to this error.
Stage Author Environment 6.4.1 (AMS)
The search rail has group predicates so that our various businesses can have a 'unique set of facets' that suits their needs in AEM Asset and their metadata schema. The filter rail is functional for all and we use permissions control what the end user accesses.
Business requested a modification to the sort order and add a few entries for an "options predicate" on their group predicate in existing search rail.
Updated the json file with the requested changes, validate code syntax, saved and confirmed changes in CRX.