Update OkHttpDataSource.java

extensions/okhttp/src/main/java/com/google/android/exoplayer2/ext/okhttp/OkHttpDataSource.java

@@ -304,13 +304,13 @@ public class OkHttpDataSource extends BaseDataSource implements HttpDataSource {
 
     // Check for a valid response code.
     if (!response.isSuccessful()) {
-      Map<String, List<String>> headers = response.headers().toMultimap();
       byte[] errorResponseBody;
       try {
         errorResponseBody = Util.toByteArray(Assertions.checkNotNull(responseByteStream));
       } catch (IOException e) {
         errorResponseBody = Util.EMPTY_BYTE_ARRAY;
       }
+      Map<String, List<String>> headers = response.headers().toMultimap();
       closeConnectionQuietly();
       InvalidResponseCodeException exception =
           new InvalidResponseCodeException(