appview/labels: reduce the opset after validation

validation also performs a transformation upon labels: it resolves
handles to DIDs, it is important that this transform be present when
determining redundant ops.

Signed-off-by: oppiliappan <[e-mail]>

appview/labels/labels.go

···
 		}
 	}
 
-	// reduce the opset
-	labelOps = models.ReduceLabelOps(labelOps)
-
 	for i := range labelOps {
 		def := actx.Defs[labelOps[i].OperandKey]
 		if err := l.validator.ValidateLabelOp(def, &labelOps[i]); err != nil {
···
 			return
 		}
 	}
+
+	// reduce the opset
+	labelOps = models.ReduceLabelOps(labelOps)
 
 	// next, apply all ops introduced in this request and filter out ones that are no-ops
 	validLabelOps := labelOps[:0]