rtpdec_h264: Return immediately on errors in h264_handle_packet_stap_a

Previously, errors were only logged but the code kept on trying,
and never actually returning the error as a return value.
Signed-off-by: NMartin Storsjö <martin@martin.st>

libavformat/rtpdec_h264.c

@@ -208,6 +208,7 @@ static int h264_handle_packet_stap_a(AVFormatContext *ctx, AVPacket *pkt,
             } else {
                 av_log(ctx, AV_LOG_ERROR,
                        "nal size exceeds length: %d %d\n", nal_size, src_len);
+                return AVERROR_INVALIDDATA;
             }
 
             // eat what we handled