Corrected an error with the new off-grid DRC check that can cause

a crash condition during GDS read-in.

VERSION

@@ -1 +1 @@
-8.3.126
+8.3.127

drc/DRCsubcell.c

@@ -647,6 +647,7 @@ void
 DRCOffGridError(rect)
     Rect      *rect;            /* Area of error */
 {
+    if (drcSubFunc == NULL) return;
     (*drcSubFunc)(DRCErrorDef, rect, &drcOffGridCookie, drcSubClientData);
 }