Fix a couple of typos found in parser_impl.cc

Change-Id: Ice4047838ad5c5e48803d8a529f3ca24d2ce77c5
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/31262
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Commit-Queue: dan sinclair <dsinclair@chromium.org>
Commit-Queue: Ben Clayton <bclayton@google.com>
diff --git a/src/reader/wgsl/parser_impl.cc b/src/reader/wgsl/parser_impl.cc
index 09f5348..ac1f606 100644
--- a/src/reader/wgsl/parser_impl.cc
+++ b/src/reader/wgsl/parser_impl.cc
@@ -1107,10 +1107,6 @@
     set_error(peek(), "invalid type alias");
     return nullptr;
   }
-  if (type == nullptr) {
-    set_error(peek(), "invalid type for alias");
-    return nullptr;
-  }
 
   auto* alias =
       ctx_.type_mgr().Get(std::make_unique<ast::type::AliasType>(name, type));
@@ -1674,7 +1670,7 @@
   for (;;) {
     auto deco = struct_member_decoration();
     if (has_error())
-      return {};
+      return false;
     if (deco == nullptr)
       break;