fix a bug

.github/workflows/main.yml

@@ -23,8 +23,6 @@ jobs:
     steps:
     - uses: actions/checkout@v2
     - uses: mymindstorm/setup-emsdk@v11
-      with:
-        emsdk-version: 3.1.25
     - name: Compiling
       run: |
         bash build_wasm.sh

src/error.h

@@ -81,6 +81,6 @@ private:
         return ss.str();
     }
 public:
-    RuntimeError(_Str type, _Str msg, std::stack<_Str> snapshots)
+    RuntimeError(_Str type, _Str msg, const std::stack<_Str>& snapshots)
         : _Error(type, msg, __concat(snapshots)) {}
 };