fix: dirty union bug

bug repro: https://stackblitz.com/edit/stackblitz-starters-swdj3e?file=index.test.js&startScript=test

src/__tests__/unions.test.ts

@@ -62,3 +62,23 @@ test("readonly union", async () => {
   union.parse("asdf");
   union.parse(12);
 });
+
+test("union of strict objects", async () => {
+  // ensure bug in 3.23.8 is fixed, where "dirty" parse failures would mean reporting the first error, rather than a proper `invalid_union` with `unionErrors`.
+  // Demo of bug: https://stackblitz.com/edit/stackblitz-starters-swdj3e?file=index.test.js&startScript=test
+  const union = z.union([
+    z.object({ x: z.number() }).strict(), //
+    z.object({ y: z.number() }).strict(),
+  ]);
+  expect(union.safeParse({ x: 1, y: 1 })).toMatchObject({
+    success: false,
+    error: {
+      issues: [
+        {
+          code: "invalid_union",
+          unionErrors: [expect.any(z.ZodError), expect.any(z.ZodError)],
+        },
+      ],
+    },
+  });
+});

src/types.ts

@@ -2987,8 +2987,6 @@ export class ZodUnion<T extends ZodUnionOptions> extends ZodType<
         })
       ).then(handleResults);
     } else {
-      let dirty: undefined | { result: DIRTY<any>; ctx: ParseContext } =
-        undefined;
       const issues: ZodIssue[][] = [];
       for (const option of options) {
         const childCtx: ParseContext = {
@@ -3007,20 +3005,13 @@ export class ZodUnion<T extends ZodUnionOptions> extends ZodType<
 
         if (result.status === "valid") {
           return result;
-        } else if (result.status === "dirty" && !dirty) {
-          dirty = { result, ctx: childCtx };
         }
 
         if (childCtx.common.issues.length) {
           issues.push(childCtx.common.issues);
         }
       }
 
-      if (dirty) {
-        ctx.common.issues.push(...dirty.ctx.common.issues);
-        return dirty.result;
-      }
-
       const unionErrors = issues.map((issues) => new ZodError(issues));
       addIssueToContext(ctx, {
         code: ZodIssueCode.invalid_union,