code: func (jst *Tracer) CaptureFault(env *vm.EVM, pc uint64, op vm.OpCode, gas, cost uint64, memory *vm.Memory, stack *vm.Stack, contract *vm.Contract, depth int, err error) error {
  	if jst.err == nil {
  		// Apart from the error, everything matches the previous invocation
  		jst.errorValue = new(string)
  		*jst.errorValue = err.Error()
  
  		_, err := jst.call("fault", "log", "db")
  		if err != nil {
  			jst.err = wrapError("fault", err)
  		}
  	}
  	return nil
  }
docs: // CaptureFault implements the Tracer interface to trace an execution fault
  // while running an opcode.