use unwrap_or to get default value

src/main.rs

@@ -8,5 +8,7 @@ fn add_10(value: Option<u32>) -> Result<u32, String> {
 fn main() {
     let value = add_10(None);
 
-    println!("Result is: {}", value.unwrap());
+    println!("Result is: {}", value.unwrap_or(42));
+
+    panic!("Non recoverable error.");
 }