From a8f268cfc00683e83aceb30e1a3e719716897b93 Mon Sep 17 00:00:00 2001
From: Isaac Hunja <isaac@kaara.works>
Date: Fri, 6 Mar 2026 07:51:33 +0300
Subject: [PATCH] fix(form-core): exclude undefined from FormState errors type

The runtime code filters out undefined values from the errorMap when
building the errors array (via .filter(val => val !== undefined)),
but the type definition allowed undefined in the union. This forced
consumers to add unnecessary runtime undefined checks when iterating
over errors.

Wrapping the error union with NonNullable aligns the type with the
actual runtime behavior.

Fixes #2022
---
 packages/form-core/src/FormApi.ts | 44 +++++++++++++++++--------------
 1 file changed, 24 insertions(+), 20 deletions(-)

diff --git a/packages/form-core/src/FormApi.ts b/packages/form-core/src/FormApi.ts
index d78c39a8a..ab3712681 100644
--- a/packages/form-core/src/FormApi.ts
+++ b/packages/form-core/src/FormApi.ts
@@ -644,16 +644,18 @@ export type DerivedFormState<
    * The error array for the form itself.
    */
   errors: Array<
-    | UnwrapFormValidateOrFn<TOnMount>
-    | UnwrapFormValidateOrFn<TOnChange>
-    | UnwrapFormAsyncValidateOrFn<TOnChangeAsync>
-    | UnwrapFormValidateOrFn<TOnBlur>
-    | UnwrapFormAsyncValidateOrFn<TOnBlurAsync>
-    | UnwrapFormValidateOrFn<TOnSubmit>
-    | UnwrapFormAsyncValidateOrFn<TOnSubmitAsync>
-    | UnwrapFormValidateOrFn<TOnDynamic>
-    | UnwrapFormAsyncValidateOrFn<TOnDynamicAsync>
-    | UnwrapFormAsyncValidateOrFn<TOnServer>
+    NonNullable<
+      | UnwrapFormValidateOrFn<TOnMount>
+      | UnwrapFormValidateOrFn<TOnChange>
+      | UnwrapFormAsyncValidateOrFn<TOnChangeAsync>
+      | UnwrapFormValidateOrFn<TOnBlur>
+      | UnwrapFormAsyncValidateOrFn<TOnBlurAsync>
+      | UnwrapFormValidateOrFn<TOnSubmit>
+      | UnwrapFormAsyncValidateOrFn<TOnSubmitAsync>
+      | UnwrapFormValidateOrFn<TOnDynamic>
+      | UnwrapFormAsyncValidateOrFn<TOnDynamicAsync>
+      | UnwrapFormAsyncValidateOrFn<TOnServer>
+    >
   >
   /**
    * A boolean indicating if any of the form fields are currently validating.
@@ -2642,16 +2644,18 @@ export class FormApi<
   getAllErrors = (): {
     form: {
       errors: Array<
-        | UnwrapFormValidateOrFn<TOnMount>
-        | UnwrapFormValidateOrFn<TOnChange>
-        | UnwrapFormAsyncValidateOrFn<TOnChangeAsync>
-        | UnwrapFormValidateOrFn<TOnBlur>
-        | UnwrapFormAsyncValidateOrFn<TOnBlurAsync>
-        | UnwrapFormValidateOrFn<TOnSubmit>
-        | UnwrapFormAsyncValidateOrFn<TOnSubmitAsync>
-        | UnwrapFormValidateOrFn<TOnDynamic>
-        | UnwrapFormAsyncValidateOrFn<TOnDynamicAsync>
-        | UnwrapFormAsyncValidateOrFn<TOnServer>
+        NonNullable<
+          | UnwrapFormValidateOrFn<TOnMount>
+          | UnwrapFormValidateOrFn<TOnChange>
+          | UnwrapFormAsyncValidateOrFn<TOnChangeAsync>
+          | UnwrapFormValidateOrFn<TOnBlur>
+          | UnwrapFormAsyncValidateOrFn<TOnBlurAsync>
+          | UnwrapFormValidateOrFn<TOnSubmit>
+          | UnwrapFormAsyncValidateOrFn<TOnSubmitAsync>
+          | UnwrapFormValidateOrFn<TOnDynamic>
+          | UnwrapFormAsyncValidateOrFn<TOnDynamicAsync>
+          | UnwrapFormAsyncValidateOrFn<TOnServer>
+        >
       >
       errorMap: ValidationErrorMap<
         UnwrapFormValidateOrFn<TOnMount>,