940c6ebd780d605aea366daae090015d8493217e
braney
  Thu Feb 23 13:07:44 2017 -0800
don't crash on bigBed3's without extra fields

diff --git src/hg/hgTracks/bigBedTrack.c src/hg/hgTracks/bigBedTrack.c
index 02cc6b4..869b6d0 100644
--- src/hg/hgTracks/bigBedTrack.c
+++ src/hg/hgTracks/bigBedTrack.c
@@ -117,30 +117,31 @@
 char *field = NULL;
 if (fieldIdx < restCount)
     field = cloneString(restFields[fieldIdx]);
 freeMem(rest);
 return field;
 }
 
 
 char *makeLabel(struct track *track,  struct bigBedInterval *bb)
 // Build a label for a bigBedTrack from the requested label fields.
 {
 char *labelSeparator = stripEnclosingDoubleQuotes(trackDbSettingClosestToHome(track->tdb, "labelSeparator"));
 if (labelSeparator == NULL)
     labelSeparator = "/";
 char *restFields[256];
+if (bb->rest != NULL)
     chopTabs(cloneString(bb->rest), restFields);
 struct dyString *dy = newDyString(128);
 boolean firstTime = TRUE;
 struct slInt *labelInt = track->labelColumns;
 for(; labelInt; labelInt = labelInt->next)
     {
     if (!firstTime)
         dyStringAppend(dy, labelSeparator);
 
     switch(labelInt->val)
         {
         case 0:
             dyStringAppend(dy, chromName);
             break;
         case 1: