Simplify offset method error handling

Author: nunoplopes

libcc2rs/src/rc.rs

@@ -297,10 +297,7 @@ impl<T> Ptr<T> {
 
     #[inline]
     pub fn offset(&self, offset: impl TryInto<isize>) -> Self {
-        let offset = match offset.try_into() {
-            Ok(o) => o,
-            Err(_) => panic!("the offset must fit in a isize"),
-        };
+        let offset = offset.try_into().expect("the offset must fit in a isize");
         let step = self.elem_step();
         Self {
             kind: self.kind.clone(),