demux: adaptative: handle peek error code (fix #15819)

modules/demux/adaptative/adaptative.cpp

@@ -161,8 +161,10 @@ static int Open(vlc_object_t *p_obj)
         {
             /* We need to probe content */
             const uint8_t *p_peek;
-            const size_t i_peek = stream_Peek(p_demux->s, &p_peek, 2048);
-            stream_t *peekstream = stream_MemoryNew(p_demux, const_cast<uint8_t *>(p_peek), i_peek, true);
+            const ssize_t i_peek = stream_Peek(p_demux->s, &p_peek, 2048);
+            if(i_peek > 0)
+            {
+                stream_t *peekstream = stream_MemoryNew(p_demux, const_cast<uint8_t *>(p_peek), (size_t)i_peek, true);
                 if(peekstream)
                 {
                     if(xmlParser.reset(peekstream) && xmlParser.parse(false))
@@ -180,6 +182,7 @@ static int Open(vlc_object_t *p_obj)
                 }
             }
         }
+    }
 
     if(!p_manager || !p_manager->start())
     {