Use ? operator in tests.

tests/engine.rs

@@ -4,7 +4,7 @@ use rhai::{Engine, EvalAltResult};
 fn test_engine_call_fn() -> Result<(), EvalAltResult> {
     let mut engine = Engine::new();
 
-    let ast = Engine::compile("fn hello(x, y) { x.len() + y }")?;
+    let ast = engine.compile("fn hello(x, y) { x.len() + y }")?;
 
     let result: i64 = engine.call_fn("hello", &ast, (&mut String::from("abc"), &mut 123_i64))?;
 

tests/var_scope.rs

@@ -40,9 +40,9 @@ fn test_scope_eval() -> Result<(), EvalAltResult> {
         .expect("y and z not found?");
 
     // Second invocation using the same state
-    if let Ok(result) = engine.eval_with_scope::<i64>(&mut scope, "x") {
-        println!("result: {}", result); // should print 966
-    }
+    let result = engine.eval_with_scope::<i64>(&mut scope, "x")?;
+
+    println!("result: {}", result); // should print 966
 
     // Variable y is changed in the script
     assert_eq!(scope.get_value::<i64>("y").unwrap(), 1);