Add tests

tests/cases/conformance/expressions/propertyAccess/propertyAccessWidening.ts

@@ -0,0 +1,22 @@
+// @strict: true
+
+// Repro from #31762
+
+function g1(headerNames: any) {
+    let t = [{ hasLineBreak: false, cells: [] }];
+    const table = [{cells: headerNames }].concat(t);
+}
+
+function g2(headerNames: any) {
+    let t = [{ hasLineBreak: false, cells: [] }];
+    const table = [{cells: headerNames }]["concat"](t);
+}
+
+// Object in property or element access is widened when target of assignment
+
+function foo(options?: { a: string, b: number }) {
+    let x1 = (options || {}).a;     // Object type not widened
+    let x2 = (options || {})["a"];  // Object type not widened
+    (options || {}).a = 1;          // Object type widened, error
+    (options || {})["a"] = 1;       // Object type widened, error
+}