replace assert with non-fatal check for mode conflict, if true return BLK_FAILED_FEASIBLE

Author: KA7E

vpr/src/pack/cluster_util.cpp

@@ -1232,7 +1232,9 @@ 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 (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];
@@ -3688,4 +3690,4 @@ void init_clb_atoms_lookup(vtr::vector<ClusterBlockId, std::unordered_set<AtomBl
 
         atoms_lookup[clb_index].insert(atom_blk_id);
     }
-}
+}