Fix panic: cannot consume from pending buffer

Fixed #298

Signed-off-by: Jiahao XU <[email protected]>

Author: NobodyXu

src/futures/bufread/generic/decoder.rs

@@ -88,21 +88,22 @@ impl<R: AsyncBufRead, D: Decode> Decoder<R, D> {
                         State::Flushing
                     } else {
                         let mut input = PartialBuffer::new(input);
-                        let done = this.decoder.decode(&mut input, output).or_else(|err| {
+                        let res = this.decoder.decode(&mut input, output).or_else(|err| {
                             // ignore the first error, occurs when input is empty
                             // but we need to run decode to flush
                             if first {
                                 Ok(false)
                             } else {
                                 Err(err)
                             }
-                        })?;
+                        });
 
                         first = false;
 
                         let len = input.written().len();
                         this.reader.as_mut().consume(len);
-                        if done {
+
+                        if res? {
                             State::Flushing
                         } else {
                             State::Decoding

src/tokio/bufread/generic/decoder.rs

@@ -88,21 +88,22 @@ impl<R: AsyncBufRead, D: Decode> Decoder<R, D> {
                         State::Flushing
                     } else {
                         let mut input = PartialBuffer::new(input);
-                        let done = this.decoder.decode(&mut input, output).or_else(|err| {
+                        let res = this.decoder.decode(&mut input, output).or_else(|err| {
                             // ignore the first error, occurs when input is empty
                             // but we need to run decode to flush
                             if first {
                                 Ok(false)
                             } else {
                                 Err(err)
                             }
-                        })?;
+                        });
 
                         first = false;
 
                         let len = input.written().len();
                         this.reader.as_mut().consume(len);
-                        if done {
+
+                        if res? {
                             State::Flushing
                         } else {
                             State::Decoding