Add a test for when a cast fails

compiler/noirc_frontend/src/tests.rs

@@ -2744,3 +2744,25 @@ fn do_not_eagerly_error_on_cast_on_type_variable() {
     "#;
     assert_no_errors(src);
 }
+
+#[test]
+fn error_on_cast_over_type_variable() {
+    let src = r#"
+    pub fn foo<T, U>(x: T, f: fn(T) -> U) -> U {
+        f(x)
+    }
+
+    fn main() {
+        let x = "a";
+        let _: Field = foo(x, |x| x as Field);
+    }
+    "#;
+
+    let errors = get_program_errors(src);
+    assert_eq!(errors.len(), 1);
+
+    assert!(matches!(
+        errors[0].0,
+        CompilationError::TypeError(TypeCheckError::TypeMismatch { .. })
+    ));
+}