feat: add support for root validation error

With this change, `_root` is now a reserved key in `validationError` object. In some cases it's
useful to define a global validation error in your Zod schema, using `.superRefine(input, ctx)`,
without specifing a path in `ctx.addIssue()`. Now it's returned to the client, when defined.

packages/next-safe-action/src/server.ts

@@ -44,12 +44,13 @@ export const createSafeActionClient = <Context>(createOpts?: {
 				const parsedInput = await schema.safeParseAsync(clientInput);
 
 				if (!parsedInput.success) {
-					const fieldErrors = parsedInput.error.flatten().fieldErrors as Partial<
-						Record<keyof z.input<typeof schema>, string[]>
-					>;
+					const { formErrors, fieldErrors } = parsedInput.error.flatten();
 
 					return {
-						validationError: fieldErrors,
+						validationError: {
+							_root: formErrors && formErrors.length ? formErrors : undefined,
+							...fieldErrors,
+						} as Partial<Record<keyof z.input<Schema> | "_root", string[]>>,
 					};
 				}
 

packages/next-safe-action/src/types.ts

@@ -8,7 +8,7 @@ import type { z } from "zod";
 export type SafeAction<Schema extends z.ZodTypeAny, Data> = (input: z.input<Schema>) => Promise<{
 	data?: Data;
 	serverError?: string;
-	validationError?: Partial<Record<keyof z.input<Schema>, string[]>>;
+	validationError?: Partial<Record<keyof z.input<Schema> | "_root", string[]>>;
 }>;
 
 /**