fix null-deref warning in GridTileLookup constructor

Author: soheilshahrouz

vpr/src/place/grid_tile_lookup.cpp

@@ -1,16 +1,10 @@
 #include "grid_tile_lookup.h"
 
-GridTileLookup::GridTileLookup() {
+GridTileLookup::GridTileLookup()
+    : max_placement_locations(g_vpr_ctx.device().logical_block_types.size()) {
     const auto& device_ctx = g_vpr_ctx.device();
     const int num_layers = device_ctx.grid.get_num_layers();
 
-    if (device_ctx.logical_block_types.empty()) {
-        throw std::runtime_error("Logical block types are empty.");
-    } else {
-        // Will store the max number of tile locations for each logical block type
-        max_placement_locations.resize(device_ctx.logical_block_types.size());
-    }
-
     for (const auto& type : device_ctx.logical_block_types) {
         vtr::NdMatrix<int, 3> type_count({static_cast<unsigned long>(num_layers), device_ctx.grid.width(), device_ctx.grid.height()});
         fill_type_matrix(&type, type_count);