Fix variables declared twice with tuple assignment

trans/transpiler/phases/emit_cpp/block.py

@@ -131,7 +131,7 @@ class BlockVisitor(NodeVisitor):
     def visit_lvalue(self, lvalue: ast.expr, declare: bool | list[bool] = False) -> Iterable[str]:
         if isinstance(lvalue, ast.Tuple):
             for name, decl, ty in zip(lvalue.elts, declare, lvalue.type.args):
-                if declare:
+                if decl:
                     yield from self.visit_lvalue(name, True)
                     yield ";"
             yield f"std::tie({', '.join(flatmap(self.visit_lvalue, lvalue.elts))})"