Fix typing bug hiding errors of nullable composite fields (#1545)

This commit changes types to match what the existing code produces.

For type: `z.object({ foo: z.string() })`
The error type was and still is `{ _errors: string[], foo?: { _errors: string[] } }`

But for type: `z.object({ foo: z.string() }).optional()`
It was previously `{ _errors: string[] }`
After this commit, it is `{ _errors: string[], foo?: { _errors: string[] } }`

deno/lib/ZodError.ts

@@ -165,12 +165,12 @@ export const quotelessJson = (obj: any) => {
 
 export type ZodFormattedError<T, U = string> = {
   _errors: U[];
-} & (T extends [any, ...any[]]
-  ? { [K in keyof T]?: ZodFormattedError<T[K]> }
-  : T extends any[]
-  ? { [k: number]: ZodFormattedError<T[number]> }
-  : T extends object
-  ? { [K in keyof T]?: ZodFormattedError<T[K]> }
+} & (NonNullable<T> extends [any, ...any[]]
+  ? { [K in keyof NonNullable<T>]?: ZodFormattedError<NonNullable<T>[K]> }
+  : NonNullable<T> extends any[]
+  ? { [k: number]: ZodFormattedError<NonNullable<T>[number]> }
+  : NonNullable<T> extends object
+  ? { [K in keyof NonNullable<T>]?: ZodFormattedError<NonNullable<T>[K]> }
   : unknown);
 
 export type inferFormattedError<

deno/lib/__tests__/error.test.ts

@@ -316,6 +316,47 @@ test("formatting", () => {
   }
 });
 
+test("formatting with nullable and optional fields", () => {
+  const nameSchema = z.string().refine((val) => val.length > 5);
+  const schema = z.object({
+    nullableObject: z.object({ name: nameSchema }).nullable(),
+    nullableArray: z.array(nameSchema).nullable(),
+    nullableTuple: z.tuple([nameSchema, nameSchema, z.number()]).nullable(),
+    optionalObject: z.object({ name: nameSchema }).optional(),
+    optionalArray: z.array(nameSchema).optional(),
+    optionalTuple: z.tuple([nameSchema, nameSchema, z.number()]).optional(),
+  });
+  const invalidItem = {
+    nullableObject: { name: "abcd" },
+    nullableArray: ["abcd"],
+    nullableTuple: ["abcd", "abcd", 1],
+    optionalObject: { name: "abcd" },
+    optionalArray: ["abcd"],
+    optionalTuple: ["abcd", "abcd", 1],
+  };
+  const result = schema.safeParse(invalidItem);
+  expect(result.success).toEqual(false);
+  if (!result.success) {
+    type FormattedError = z.inferFormattedError<typeof schema>;
+    const error: FormattedError = result.error.format();
+    expect(error._errors).toEqual([]);
+    expect(error.nullableObject?._errors).toEqual([]);
+    expect(error.nullableObject?.name?._errors).toEqual(["Invalid input"]);
+    expect(error.nullableArray?._errors).toEqual([]);
+    expect(error.nullableArray?.[0]?._errors).toEqual(["Invalid input"]);
+    expect(error.nullableTuple?._errors).toEqual([]);
+    expect(error.nullableTuple?.[0]?._errors).toEqual(["Invalid input"]);
+    expect(error.nullableTuple?.[1]?._errors).toEqual(["Invalid input"]);
+    expect(error.optionalObject?._errors).toEqual([]);
+    expect(error.optionalObject?.name?._errors).toEqual(["Invalid input"]);
+    expect(error.optionalArray?._errors).toEqual([]);
+    expect(error.optionalArray?.[0]?._errors).toEqual(["Invalid input"]);
+    expect(error.optionalTuple?._errors).toEqual([]);
+    expect(error.optionalTuple?.[0]?._errors).toEqual(["Invalid input"]);
+    expect(error.optionalTuple?.[1]?._errors).toEqual(["Invalid input"]);
+  }
+})
+
 const stringWithCustomError = z.string({
   errorMap: (issue, ctx) => ({
     message:

src/ZodError.ts

@@ -165,12 +165,12 @@ export const quotelessJson = (obj: any) => {
 
 export type ZodFormattedError<T, U = string> = {
   _errors: U[];
-} & (T extends [any, ...any[]]
-  ? { [K in keyof T]?: ZodFormattedError<T[K]> }
-  : T extends any[]
-  ? { [k: number]: ZodFormattedError<T[number]> }
-  : T extends object
-  ? { [K in keyof T]?: ZodFormattedError<T[K]> }
+} & (NonNullable<T> extends [any, ...any[]]
+  ? { [K in keyof NonNullable<T>]?: ZodFormattedError<NonNullable<T>[K]> }
+  : NonNullable<T> extends any[]
+  ? { [k: number]: ZodFormattedError<NonNullable<T>[number]> }
+  : NonNullable<T> extends object
+  ? { [K in keyof NonNullable<T>]?: ZodFormattedError<NonNullable<T>[K]> }
   : unknown);
 
 export type inferFormattedError<

src/__tests__/error.test.ts

@@ -315,6 +315,47 @@ test("formatting", () => {
   }
 });
 
+test("formatting with nullable and optional fields", () => {
+  const nameSchema = z.string().refine((val) => val.length > 5);
+  const schema = z.object({
+    nullableObject: z.object({ name: nameSchema }).nullable(),
+    nullableArray: z.array(nameSchema).nullable(),
+    nullableTuple: z.tuple([nameSchema, nameSchema, z.number()]).nullable(),
+    optionalObject: z.object({ name: nameSchema }).optional(),
+    optionalArray: z.array(nameSchema).optional(),
+    optionalTuple: z.tuple([nameSchema, nameSchema, z.number()]).optional(),
+  });
+  const invalidItem = {
+    nullableObject: { name: "abcd" },
+    nullableArray: ["abcd"],
+    nullableTuple: ["abcd", "abcd", 1],
+    optionalObject: { name: "abcd" },
+    optionalArray: ["abcd"],
+    optionalTuple: ["abcd", "abcd", 1],
+  };
+  const result = schema.safeParse(invalidItem);
+  expect(result.success).toEqual(false);
+  if (!result.success) {
+    type FormattedError = z.inferFormattedError<typeof schema>;
+    const error: FormattedError = result.error.format();
+    expect(error._errors).toEqual([]);
+    expect(error.nullableObject?._errors).toEqual([]);
+    expect(error.nullableObject?.name?._errors).toEqual(["Invalid input"]);
+    expect(error.nullableArray?._errors).toEqual([]);
+    expect(error.nullableArray?.[0]?._errors).toEqual(["Invalid input"]);
+    expect(error.nullableTuple?._errors).toEqual([]);
+    expect(error.nullableTuple?.[0]?._errors).toEqual(["Invalid input"]);
+    expect(error.nullableTuple?.[1]?._errors).toEqual(["Invalid input"]);
+    expect(error.optionalObject?._errors).toEqual([]);
+    expect(error.optionalObject?.name?._errors).toEqual(["Invalid input"]);
+    expect(error.optionalArray?._errors).toEqual([]);
+    expect(error.optionalArray?.[0]?._errors).toEqual(["Invalid input"]);
+    expect(error.optionalTuple?._errors).toEqual([]);
+    expect(error.optionalTuple?.[0]?._errors).toEqual(["Invalid input"]);
+    expect(error.optionalTuple?.[1]?._errors).toEqual(["Invalid input"]);
+  }
+})
+
 const stringWithCustomError = z.string({
   errorMap: (issue, ctx) => ({
     message: