smacker: fix smacker_decode_header_tree() empty vlc table init

Fixes Ticket1858
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/smacker.c

@@ -207,6 +207,7 @@ static int smacker_decode_header_tree(SmackVContext *smk, GetBitContext *gb, int
     if(get_bits1(gb)) {
         smacker_decode_tree(gb, &tmp1, 0, 0);
         skip_bits1(gb);
+        if(tmp1.current > 1) {
             res = init_vlc(&vlc[0], SMKTREE_BITS, tmp1.length,
                         tmp1.lengths, sizeof(int), sizeof(int),
                         tmp1.bits, sizeof(uint32_t), sizeof(uint32_t), INIT_VLC_LE);
@@ -214,12 +215,15 @@ static int smacker_decode_header_tree(SmackVContext *smk, GetBitContext *gb, int
                 av_log(smk->avctx, AV_LOG_ERROR, "Cannot build VLC table\n");
                 return AVERROR_INVALIDDATA;
             }
-    } else {
+        }
+    }
+    if (!vlc[0].table) {
         av_log(smk->avctx, AV_LOG_ERROR, "Skipping low bytes tree\n");
     }
     if(get_bits1(gb)){
         smacker_decode_tree(gb, &tmp2, 0, 0);
         skip_bits1(gb);
+        if(tmp2.current > 1) {
             res = init_vlc(&vlc[1], SMKTREE_BITS, tmp2.length,
                         tmp2.lengths, sizeof(int), sizeof(int),
                         tmp2.bits, sizeof(uint32_t), sizeof(uint32_t), INIT_VLC_LE);
@@ -227,7 +231,9 @@ static int smacker_decode_header_tree(SmackVContext *smk, GetBitContext *gb, int
                 av_log(smk->avctx, AV_LOG_ERROR, "Cannot build VLC table\n");
                 return AVERROR_INVALIDDATA;
             }
-    } else {
+        }
+    }
+    if (!vlc[1].table) {
         av_log(smk->avctx, AV_LOG_ERROR, "Skipping high bytes tree\n");
     }