[VPlan] Fix typo in assertion. NFC

Author: lukel97

llvm/lib/Transforms/Vectorize/VPlanPatternMatch.h

@@ -221,8 +221,9 @@ struct Recipe_match {
     if ((!matchRecipeAndOpcode<RecipeTys>(R) && ...))
       return false;
 
-    assert(R->getNumOperands() == std::tuple_size<Ops_t>::value &&
-           "recipe with matched opcode the expected number of operands");
+    assert(
+        R->getNumOperands() == std::tuple_size<Ops_t>::value &&
+        "recipe with matched opcode without the expected number of operands");
 
     auto IdxSeq = std::make_index_sequence<std::tuple_size<Ops_t>::value>();
     if (all_of_tuple_elements(IdxSeq, [R](auto Op, unsigned Idx) {