[indic] Fix access past end of array

src/hb-ot-shape-complex-indic.cc

diff --git a/src/hb-ot-shape-complex-indic.cc b/src/hb-ot-shape-complex-indic.cc
index 02087a0..5bb1f33 100644
--- a/src/hb-ot-shape-complex-indic.cc
+++ b/src/hb-ot-shape-complex-indic.cc
@@ -1372,9 +1372,10 @@
   if (base == end && start < base &&
       is_one_of (info[base - 1], FLAG (OT_ZWJ)))
     base--;
-  while (start < base &&
-	 is_one_of (info[base], (FLAG (OT_N) | HALANT_OR_COENG_FLAGS)))
-    base--;
+  if (base < end)
+    while (start < base &&
+	   is_one_of (info[base], (FLAG (OT_N) | HALANT_OR_COENG_FLAGS)))
+      base--;
 
 
   /*   o Reorder matras: