message: smt expr: fix crash
diff: @@ -1341,7 +1341,7 @@ expr expr::cmp_eq(const expr &rhs, bool simplify) const {
  if (isSignExt(a)) {
  // (sext a) == (sext b) -> a == b
  - if (rhs.isSignExt(b))
  + if (rhs.isSignExt(b) && a.bits() == b.bits())
  return a == b;
  // (sext a) == 0 -> a == 0
  