7b6ed6442a14f0d521f0f4dcc6e2b248094584a0
braney
  Wed May 25 08:25:50 2022 -0700
fix crash I introduced yesterday

diff --git src/hg/lib/hgFind.c src/hg/lib/hgFind.c
index c3b19a7..905c8f6 100644
--- src/hg/lib/hgFind.c
+++ src/hg/lib/hgFind.c
@@ -2147,31 +2147,31 @@
     errCatchFree(&errCatch);
     if (hgp->singlePos != NULL)
 	{
 	if (retMultiChrom && chrom != NULL && differentString(chrom, hgp->singlePos->chrom))
             *retMultiChrom = cloneString(chrom);
 	chrom = hgp->singlePos->chrom;
 	if (hgp->singlePos->chromStart < start)
 	    start = hgp->singlePos->chromStart;
 	if (hgp->singlePos->chromEnd > end)
 	    end = hgp->singlePos->chromEnd;
 	}
     else if (hgp->posCount == 0 || (multiTerm && hgp->posCount > 1))
         break;
     }
 if (retChromName)
-    *retChromName = chromAliasFindNative(chrom);
+    *retChromName = (chrom == NULL) ? NULL : chromAliasFindNative(chrom);
 if (retWinStart)
     *retWinStart  = start;
 if (retWinEnd)
     *retWinEnd    = end;
 return hgp;
 }
 
 static struct hgPositions *revertPosition(struct cart *cart, char **pPosition,
                                           char **retChrom, int *retStart, int *retEnd,
                                           char *hgAppName, struct dyString *dyWarn)
 /* Revert *pPosition to lastPosition (or default position).  Return a new hgp for the
  * resolved position.  Append warnings to dyWarn, errAbort if defaultPos doesn't work.  */
 {
 struct hgPositions *hgp = NULL;
 boolean isMultiTerm = FALSE;