avformat/mov: Propagate errors in mov_switch_root.

Signed-off-by: Jacob Trimble <modmaker@google.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 2d9cf3bf16)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/mov.c

@@ -6418,6 +6418,7 @@ static int should_retry(AVIOContext *pb, int error_code) {
 
 static int mov_switch_root(AVFormatContext *s, int64_t target)
 {
+    int ret;
     MOVContext *mov = s->priv_data;
     int i, j;
     int already_read = 0;
@@ -6454,8 +6455,10 @@ static int mov_switch_root(AVFormatContext *s, int64_t target)
 
     mov->found_mdat = 0;
 
-    if (mov_read_default(mov, s->pb, (MOVAtom){ AV_RL32("root"), INT64_MAX }) < 0 ||
-        avio_feof(s->pb))
+    ret = mov_read_default(mov, s->pb, (MOVAtom){ AV_RL32("root"), INT64_MAX });
+    if (ret < 0)
+        return ret;
+    if (avio_feof(s->pb))
         return AVERROR_EOF;
     av_log(s, AV_LOG_TRACE, "read fragments, offset 0x%"PRIx64"\n", avio_tell(s->pb));