Core: Fix func expression simplify

src/App/Expression.cpp

@@ -2610,7 +2610,7 @@ Py::Object FunctionExpression::_getPyValue() const {
 Expression *FunctionExpression::simplify() const
 {
     size_t numerics = 0;
-    std::vector<Expression*> a;
+    std::vector<Expression*> simplifiedArgs;
 
     // Try to simplify each argument to function
     for (auto it : args) {
@@ -2618,20 +2618,21 @@ Expression *FunctionExpression::simplify() const
 
         if (freecad_cast<NumberExpression*>(v))
             ++numerics;
-        a.push_back(v);
+        simplifiedArgs.push_back(v);
     }
 
     if (numerics == args.size()) {
         // All constants, then evaluation must also be constant
 
-        // Clean-up
-        for (auto it : args)
+        // Clean-up the simplified arguments
+        for (auto it : simplifiedArgs)
             delete it;
 
         return eval();
     }
     else
-        return new FunctionExpression(owner, f, std::string(fname), std::move(a));
+        return new FunctionExpression(owner, f, std::string(fname),
+                                      std::move(simplifiedArgs));
 }
 
 /**