fix: Fix panic caused when arg is nil (#3353)

Author: frankxjkuang

commands.go

@@ -81,6 +81,8 @@ func appendArg(dst []interface{}, arg interface{}) []interface{} {
 		return dst
 	case time.Time, time.Duration, encoding.BinaryMarshaler, net.IP:
 		return append(dst, arg)
+	case nil:
+		return dst
 	default:
 		// scan struct field
 		v := reflect.ValueOf(arg)

commands_test.go

@@ -7209,6 +7209,17 @@ var _ = Describe("Commands", func() {
 			Expect(err).NotTo(HaveOccurred())
 			Expect(vals).To(Equal([]interface{}{int64(12), proto.RedisError("error"), "abc"}))
 		})
+
+		It("returns empty values when args are nil", func() {
+			vals, err := client.Eval(
+				ctx,
+				"return {ARGV[1]}",
+				[]string{},
+				nil,
+			).Result()
+			Expect(err).NotTo(HaveOccurred())
+			Expect(vals).To(BeEmpty())
+		})
 	})
 
 	Describe("EvalRO", func() {
@@ -7232,6 +7243,17 @@ var _ = Describe("Commands", func() {
 			Expect(err).NotTo(HaveOccurred())
 			Expect(vals).To(Equal([]interface{}{int64(12), proto.RedisError("error"), "abc"}))
 		})
+
+		It("returns empty values when args are nil", func() {
+			vals, err := client.EvalRO(
+				ctx,
+				"return {ARGV[1]}",
+				[]string{},
+				nil,
+			).Result()
+			Expect(err).NotTo(HaveOccurred())
+			Expect(vals).To(BeEmpty())
+		})
 	})
 
 	Describe("Functions", func() {