[wasm] Fix wrong DCHECK in WasmExceptionPackage

We only expect the "wasm_exception_values_symbol" property to be a fixed
array if the property actually exists. If the property is not found,
JSReceiver::GetProperty returns "undefined", so skip the check in this
case.

R=clemensb@chromium.org

Bug: chromium:1262582
Change-Id: I28d7891064bdd7632ff1a4c94ba021163401fd88
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3244416
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77685}

src/wasm/wasm-objects.cc

@@ -1793,7 +1793,7 @@ Handle<Object> WasmExceptionPackage::GetExceptionValues(
           isolate, exception_package,
           isolate->factory()->wasm_exception_values_symbol())
           .ToHandle(&values)) {
-    DCHECK(values->IsFixedArray());
+    DCHECK_IMPLIES(!values->IsUndefined(), values->IsFixedArray());
     return values;
   }
   return ReadOnlyRoots(isolate).undefined_value_handle();