fix: correctly initialize evaluated properties with nested anyOf (etc…

….), closes #1515

lib/compile/util.ts

@@ -128,7 +128,7 @@ export const mergeEvaluated: MergeEvaluated = {
         gen.if(
           _`${from} === true`,
           () => gen.assign(to, true),
-          () => gen.code(_`Object.assign(${to}, ${from})`)
+          () => gen.assign(to, _`${to} || {}`).code(_`Object.assign(${to}, ${from})`)
         )
       }),
     mergeToName: (gen, from, to) =>

spec/issues/1515_evaluated_properties_nested_anyof.spec.ts

@@ -0,0 +1,28 @@
+import _Ajv from "../ajv2019"
+import * as assert from "assert"
+
+describe("tracking evaluated properties with nested anyOf", () => {
+  it("should initialize evaluated properties", () => {
+    const ajv = new _Ajv()
+
+    const schema = {
+      type: "object",
+      anyOf: [
+        {
+          required: ["foo"],
+          properties: {foo: {}},
+        },
+        {
+          anyOf: [
+            {
+              properties: {bar: {}},
+            },
+          ],
+        },
+      ],
+    }
+
+    const validate = ajv.compile(schema)
+    assert.strictEqual(validate({bar: 1}), true)
+  })
+})