to: Allow the user string to be empty to get the remaining information

src/chatgpt-api.ts

@@ -331,7 +331,8 @@ export class ChatGPTAPI {
     }
 
     const systemMessageOffset = messages.length
-    let nextMessages = messages.concat([
+    let nextMessages = text
+      ? messages.concat([
           {
             ...{
               role: 'user',
@@ -340,6 +341,7 @@ export class ChatGPTAPI {
             }
           }
         ])
+      : messages
     let numTokens = 0
 
     do {