// The bug happened like this:
//  1. The main binary adds an itab for *json.UnsupportedValueError / error
//     (concrete type / interface type).  This itab goes in hash bucket 0x111.
//  2. The plugin adds that same itab again.  That makes a cycle in the itab
//     chain rooted at hash bucket 0x111.
//  3. The main binary then asks for the itab for *dynamodbstreamsevt.Event /