refactor: use match when processing EchidnaCoreEditor's initial file

Just like in 8e31be7.

src/components/editor/mod.rs

@@ -21,8 +21,8 @@ impl EchidnaCoreEditor {
         // Without cloning it, for some reasons the Rust compiler complains about &this.to_imp().sourceview not being IsA<sourceview::View>
         this_imp.minimap.set_view(&this_imp.sourceview.clone());
 
-        if file.is_some() {
-            let file = file.unwrap();
+        match file {
+            Some(file) => {
                 let file_location = file
                     .location()
                     .expect("file is required to have a location");
@@ -73,6 +73,8 @@ impl EchidnaCoreEditor {
                 );
                 }
             }
+            None => {}
+        }
         this
     }