improve error handling

src/backend/rust.rs

@@ -21,14 +21,15 @@ impl Backend for Rust {
     impl_backend_constants!();
 
     fn get_all_installed_packages(&self) -> Result<HashSet<Package>> {
-        let file = get_crates_file().unwrap();
-        let content = read_to_string(file).unwrap();
-        let json: Value = serde_json::from_str(&content).unwrap();
-        extract_packages(json)
+        let file = get_crates_file().context("getting path to crates file")?;
+        let content = read_to_string(file).context("reading crates file")?;
+        let json: Value = serde_json::from_str(&content).context("parsing JSON")?;
+        extract_packages(json).context("extracing packages from JSON")
     }
 
     fn get_explicitly_installed_packages(&self) -> Result<HashSet<Package>> {
         self.get_all_installed_packages()
+            .context("getting all installed packages")
     }
 }