wasm: add missing init reported by coverity

Signed-off-by: Michael Dawson <mdawson@devrus.com>

PR-URL: #42897
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Mohammed Keyvanzadeh <mohammadkeyvanzade94@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Mestery <mestery@protonmail.com>

src/node_wasm_web_api.h

@@ -39,7 +39,7 @@ class WasmStreamingObject final : public BaseObject {
   static void Abort(const v8::FunctionCallbackInfo<v8::Value>& args);
 
   std::shared_ptr<v8::WasmStreaming> streaming_;
-  size_t wasm_size_;
+  size_t wasm_size_ = 0;
 };
 
 // This is a v8::WasmStreamingCallback implementation that must be passed to