player: simplify logic on video errors

Fatal errors in the vidoe chain (such as failing to initialize the video
chain) disable video decoding. Restart the playloop, instead of just
continuing the current iteration.

The resulting behavior should be the same, but it gets rid of possible
corner cases.

player/playloop.c

@@ -968,7 +968,7 @@ void run_playloop(struct MPContext *mpctx)
                 mpctx->stop_play = PT_NEXT_ENTRY;
             mpctx->error_playing = true;
             handle_force_window(mpctx, true);
-            break;
+            return; // restart loop
         }
 
         if (r == VD_EOF) {