Merge pull request verilog-to-routing#2433 from verilog-to-routing/ma…

…ke_mode_conflict_non_fatal

replace assert with non-fatal check for mode conflict

vpr/src/pack/cluster_util.cpp

@@ -1243,7 +1243,10 @@ enum e_block_pack_status try_place_atom_block_rec(const t_pb_graph_node* pb_grap
             }
         }
     } else {
-        VTR_ASSERT(parent_pb->mode == pb_graph_node->pb_type->parent_mode->index);
+       /* if this is not the first child of this parent, must match existing parent mode */
+       if (parent_pb->mode != pb_graph_node->pb_type->parent_mode->index) {
+            return BLK_FAILED_FEASIBLE;
+        }
     }
 
     const t_mode* mode = &parent_pb->pb_graph_node->pb_type->modes[parent_pb->mode];