feat: support dify (close #299)

controller/channel-test.go

@@ -67,7 +67,11 @@ func testChannel(channel *model.Channel, testModel string) (err error, openaiErr
 		if channel.TestModel != nil && *channel.TestModel != "" {
 			testModel = *channel.TestModel
 		} else {
-			testModel = adaptor.GetModelList()[0]
+			if len(adaptor.GetModelList()) > 0 {
+				testModel = adaptor.GetModelList()[0]
+			} else {
+				testModel = "gpt-3.5-turbo"
+			}
 		}
 	} else {
 		modelMapping := *channel.ModelMapping