[fine] Error checking for some cases

fine/src/semantics.rs

@@ -1375,7 +1375,14 @@ impl<'a> Semantics<'a> {
         // Form 2: { x, ... }
         let environment = self.environment_of(t);
         let id = tree.nth_token(0)?;
-        match environment.bind(id)? {
+        let declaration = match environment.bind(id) {
+            Some(d) => d,
+            None => {
+                self.report_error_tree(tree, format!("cannot find value {id} here"));
+                return Some(Type::Error);
+            }
+        };
+        match declaration {
             Declaration::Variable {
                 declaration_type, ..
             }
@@ -1662,7 +1669,7 @@ fn check_new_object_expression(s: &Semantics, tree: &Tree) {
                         s.report_error_tree_ref(
                             *field_tree,
                             format!(
-                                "field {} has is of type {}, but this expression generates a {}",
+                                "field {} is of type {}, but this expression generates a {}",
                                 f.name, f.field_type, expr_type,
                             ),
                         );

fine/tests/expression/errors/class_errors.fine

@@ -0,0 +1,24 @@
+class Point {
+  x: f64;
+  y: f64;
+}
+
+fun test() {
+  let one = new Point { x: 23 };
+  let two = new Point { y: 23 };
+  let three = new Point { y: 23, x: 123, z: "hello" };
+  let four = new Point { y: 23, x: "what" };
+
+  let five = new Point { y: 23, x };
+
+  let x = "now";
+  let six = new Point { y: 23, x };
+}
+
+// @expect-errors:
+// | 7:12: missing an initializer for field y
+// | 8:12: missing an initializer for field x
+// | 9:41: class Point does not have a field named z
+// | 10:32: field x is of type f64, but this expression generates a string
+// | 12:32: cannot find value x here
+// | 15:31: field x is of type f64, but this expression generates a string