types: add generics to isError and update DataT default generic param (#582)

Author: DamianGlowala

src/error.ts

@@ -19,7 +19,7 @@ import { hasProp } from "./utils/internal/object";
  *                         This can be used to pass additional information about the error.
  * @property {boolean} internal - Setting this property to `true` will mark the error as an internal error.
  */
-export class H3Error<DataT = any> extends Error {
+export class H3Error<DataT = unknown> extends Error {
   static __h3_error__ = true;
   statusCode = 500;
   fatal = false;
@@ -64,16 +64,16 @@ export class H3Error<DataT = any> extends Error {
  * @param input {string | (Partial<H3Error> & { status?: number; statusText?: string })} - The error message or an object containing error properties.
  * @return {H3Error} - An instance of H3Error.
  */
-export function createError<DataT = any>(
+export function createError<DataT = unknown>(
   input:
     | string
     | (Partial<H3Error<DataT>> & { status?: number; statusText?: string }),
-): H3Error {
+) {
   if (typeof input === "string") {
     return new H3Error<DataT>(input);
   }
 
-  if (isError(input)) {
+  if (isError<DataT>(input)) {
     return input;
   }
 
@@ -177,6 +177,6 @@ export function sendError(
  * @param input {*} - The input to check.
  * @return {boolean} - Returns true if the input is an instance of H3Error, false otherwise.
  */
-export function isError(input: any): input is H3Error {
+export function isError<DataT = unknown>(input: any): input is H3Error<DataT> {
   return input?.constructor?.__h3_error__ === true;
 }