[vpr][base] fix switch id access

Author: amin1377

vpr/src/base/stats.cpp

@@ -244,8 +244,8 @@ void write_sb_count_stats(const Netlist<>& net_list,
                 RRNodeId sink_node = rt_node.inode;
                 std::vector<RREdgeId> edges = rr_graph.find_edges(src_node, sink_node);
                 VTR_ASSERT(edges.size() == 1);
-                RRSwitchId rr_switch_id = rr_graph.edge_switch(edges[0]);
-                const std::string& sw_template_id = rr_graph.rr_switch_inf(rr_switch_id).template_id;
+                RRSwitchId switch_id = RRSwitchId(rr_graph.edge_switch(edges[0]));
+                const std::string& sw_template_id = rr_graph.rr_switch_inf(switch_id).template_id;
                 if (sw_template_id.empty()) {
                     continue;
                 }