7eb7071e960db1722c1597e2d2f7b113868efbb2
braney
  Mon Sep 26 14:37:45 2022 -0700
in intersection graphs in pack mode, don't descedn into the linkFeatures
draw code if there are no items because thar be dragons

diff --git src/hg/hgTracks/interactTrack.c src/hg/hgTracks/interactTrack.c
index d701be3..a0b9dd8 100644
--- src/hg/hgTracks/interactTrack.c
+++ src/hg/hgTracks/interactTrack.c
@@ -871,30 +871,31 @@
 }
 
 void interactDrawItems(struct track *tg, int seqStart, int seqEnd,
         struct hvGfx *hvg, int xOff, int yOff, int width, 
         MgFont *font, Color color, enum trackVisibility vis)
 /* Draw a list of interact structures. */
 {
 struct interactTrackInfo *tInfo = (struct interactTrackInfo *)tg->customPt;
 #ifdef MR_FORCE_PACK
 if (tInfo->clusterMode || isLinkedFeaturesMode(tg) || differentString(virtModeType, "default"))
 #else
 if (tInfo->clusterMode || isLinkedFeaturesMode(tg))
 #endif
     {
     tg->drawItemAt = interactLinkedFeaturesDrawAt;
+    if (tg->items != NULL)
         linkedFeaturesDraw(tg, seqStart, seqEnd, hvg, xOff, yOff, width, font, color, vis);
     }
 else
     // curve, etc. connector display
     drawInteractItems(tg, seqStart, seqEnd, hvg, xOff, yOff, width, font, color, vis);
 }
 
 void interactMethods(struct track *tg)
 /* Interact track type methods */
 {
 tg->bedSize = 12;
 linkedFeaturesMethods(tg);         // for most vis and mode settings
 tg->loadItems = interactLoadItems;
 tg->itemRightPixels = interactRightPixels;
 tg->drawItems = interactDrawItems;