fix: 复合赋值旧值读改抛错读并补严格隐式全局写检查

crates/oxide_vm/tests/implicit_global_write_tests.rs

@@ -86,17 +86,19 @@ fn sloppy_update_operator_undeclared_write_lands_on_global() {
     assert!(r.is_bool() && r.as_bool(), "z++ 未声明写应落全局 NaN（undefined+1），实际 {:?}", r);
 }
 
+// ── 复合赋值：未声明名旧值读在 lval 求值步抛 ReferenceError（未解析引用不可
+// GetValue，两模式同），不物化全局 NaN ──
 #[test]
-fn sloppy_compound_operator_undeclared_write_is_nan() {
-    let s = eval_str("w += 1; typeof w");
-    assert_eq!(s, "number", "w += 1 未声明名应为 NaN（typeof number），实际 {s}");
+fn sloppy_compound_operator_undeclared_write_throws() {
+    let result = eval("w += 1");
+    assert_err_contains(result, "w is not defined");
 }
 
-// ── 逻辑赋值：未声明名 ||= 短路建全局 ──
+// ── 逻辑赋值：未声明名旧值读抛 ReferenceError，短路路径不可达，不物化全局 ──
 #[test]
-fn sloppy_logical_assign_undeclared_write_lands_on_global() {
-    let r = eval_many(&["p ||= 5", "globalThis.p === 5"]).unwrap();
-    assert!(r.is_bool() && r.as_bool(), "p ||= 5 未声明写应落全局为 5，实际 {:?}", r);
+fn sloppy_logical_assign_undeclared_write_throws() {
+    let result = eval("p ||= 5");
+    assert_err_contains(result, "p is not defined");
 }
 
 // ── for-in 左侧未声明标识符：首个键后建全局 ──

crates/oxide_vm/tests/with_fallback_implicit_global_tests.rs

@@ -59,12 +59,12 @@ fn with_fallback_declared_var_writes_outer_binding() {
 }
 
 #[test]
-fn with_fallback_compound_undeclared_write_keeps_existing_behavior() {
-    // 复合赋值回退臂走静态复合路径：未声明名旧值按 undefined 读
-    // （GetBaseValue 语义不抛），复合运算结果落隐式全局。
-    assert_eq!(
-        eval("var o={}; with(o){x+=1;} isNaN(globalThis.x)"),
-        "true",
-        "with 回退未声明名复合赋值保持既有读 undefined 行为"
+fn with_fallback_compound_undeclared_write_throws() {
+    // 复合赋值回退臂走静态复合路径：未声明名旧值读在 lval 求值步抛
+    // ReferenceError（未解析引用不可 GetValue，两模式同），不物化隐式全局。
+    let s = eval("var o={}; with(o){x+=1;}");
+    assert!(
+        s.contains("ReferenceError") && s.contains("x is not defined"),
+        "with 回退未声明名复合赋值应抛 ReferenceError，实际 {s}"
     );
 }