Leftmost edge of interior b-tree node at level <num> must have a
  NULL IKEY.
  IKEY of "<str>" found as first entry of dbkey <num>:<num>:<num>.

  Explanation:  The left edge of a b-tree must have a null Ikey at
  each  non-leaf level.  The specified b-tree node was at the left
  edge of the tree and had a non-null Ikey  as  its  first  entry.
  This indicates that the index is corrupt.

  User Action:  Drop and rebuild the index.