.

wcfs/internal/xbtree.py

@@ -108,7 +108,7 @@ class Tree(object):
                 child = children[i]
                 for k in children[i].keyv:
                     if not (klo <= k < khi):
-                        panic("children[%d] keys are outside allowed range" % i)
+                        panic("children[%d] key %d is outside allowed range [%s, %s)" % (i, k, klo, khi))
 
         t.keyv     = tuple(keyv)
         t.children = tuple(children)