add error check

cleanup

Author: amalavet

internal/simplecue/generator.go

@@ -730,15 +730,16 @@ func (g *generator) declareStringConstraints(v cue.Value) ([]ast.TypeConstraint,
 
 	for i := 0; i < len(typeAndConstraints); i++ {
 		andExpr := typeAndConstraints[i]
+		if err := andExpr.Err(); err != nil {
+			return nil, errorWithCueRef(v, "error while parsing constraints: %v", err)
+		}
+
 		op, args := andExpr.Expr()
 
 		switch op {
 		case cue.SelectorOp:
 			scope, refPath := andExpr.ReferencePath()
-			if refPath.String() != "" {
-				typeAndConstraints = append(typeAndConstraints, scope.LookupPath(refPath))
-			}
-			continue
+			typeAndConstraints = append(typeAndConstraints, scope.LookupPath(refPath))
 		case cue.CallOp:
 			// TODO: support more constraints?
 			switch fmt.Sprint(args[0]) {