wasi: address coverity warning

- add check for case when trying to provide
  a better Exception fails
- the code was modified to avoid a CHECK_EQ in all
  cases in nodejs#31076,
  however, I believe that if we fail to create the exeption
  to throw instead of simply returning using a CHECK makes
  more sense. I think it should also address the coverity
  warning about not initializing in the constructor.

Signed-off-by: Michael Dawson <midawson@redhat.com>

PR-URL: nodejs#49866
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

src/node_wasi.cc

@@ -83,8 +83,8 @@ WASI::WASI(Environment* env,
   int err = uvwasi_init(&uvw_, options);
   if (err != UVWASI_ESUCCESS) {
     Local<Value> exception;
-    if (!WASIException(env->context(), err, "uvwasi_init").ToLocal(&exception))
-      return;
+    CHECK(
+        WASIException(env->context(), err, "uvwasi_init").ToLocal(&exception));
 
     env->isolate()->ThrowException(exception);
   }