refactored data loading code

src/bin/generate_benchmark_targets.rs

@@ -1,5 +1,4 @@
-use fapra_osm_2::gridgraph::GridGraph;
-use std::fs::File;
+use fapra_osm_2::utils::load_graph;
 use clap::Parser;
 use std::process::exit;
 use rand::seq::SliceRandom;
@@ -21,21 +20,7 @@ struct Args {
 fn main() {
     let args = Args::parse();
 
-    let file = match File::open(args.graph.clone()) {
-        Ok(f) => f,
-        Err(e) => {
-            println!("Error while opening the file {}: {}", args.graph, e);
-            exit(1)
-        }
-    };
-
-    let graph = match GridGraph::from_fmi_file(file) {
-        Ok(g) => g,
-        Err(e) => {
-            println!("Error while reading the graph: {:?}", e);
-            exit(1);
-        }
-    };
+    let graph = load_graph(&args.graph);
 
     let mut rng = rand::thread_rng();