fix: 重复处理首个 chunk

src/chat/error.rs

@@ -125,6 +125,7 @@ impl ErrorResponse {
 pub enum StreamError {
     ChatError(ChatError),
     DataLengthLessThan5,
+    EmptyStream,
 }
 
 impl std::fmt::Display for StreamError {
@@ -132,6 +133,7 @@ impl std::fmt::Display for StreamError {
         match self {
             StreamError::ChatError(error) => write!(f, "{}", error.error.code),
             StreamError::DataLengthLessThan5 => write!(f, "data length less than 5"),
+            StreamError::EmptyStream => write!(f, "empty stream"),
         }
     }
 }