Catch bad tuple.extract index in parser (#3766)

Previously an out-of-bounds index would result in an out-of-bounds read during
finalization of the tuple.extract expression.

1 files changed, 1 insertions, 0 deletions

diff --git a/src/wasm/wasm.cpp b/src/wasm/wasm.cpp
index 18f8594b1..2ccd9a70a 100644
--- a/src/wasm/wasm.cpp
+++ b/src/wasm/wasm.cpp
@@ -872,6 +872,7 @@ void TupleExtract::finalize() {
   if (tuple->type == Type::unreachable) {
     type = Type::unreachable;
   } else {
+    assert(index < tuple->type.size());
     type = tuple->type[index];
   }
 }