fix tests

Author: molpopgen

examples/forward_simulation.rs

@@ -368,9 +368,9 @@ fn simplify(
         Ok(x) => match x {
             Some(idmap) => {
                 for a in alive.iter_mut() {
-                    a.node0 = idmap[usize::from(a.node0)];
+                    a.node0 = idmap[usize::try_from(a.node0).unwrap()];
                     assert!(a.node0 != tskit::NodeId::NULL);
-                    a.node1 = idmap[usize::from(a.node1)];
+                    a.node1 = idmap[usize::try_from(a.node1).unwrap()];
                     assert!(a.node1 != tskit::NodeId::NULL);
                 }
             }

src/test_simplification.rs

@@ -37,7 +37,7 @@ mod tests {
         assert!(idmap_option.is_some());
         let idmap = idmap_option.unwrap();
         for &i in samples {
-            assert_ne!(idmap[usize::from(i)], NodeId::NULL);
+            assert_ne!(idmap[usize::try_from(i).unwrap()], NodeId::NULL);
         }
     }
 }