feat: use Error.isError when available

Author: birtles

src/error.d.ts

@@ -0,0 +1,3 @@
+interface ErrorConstructor {
+  isError(error: unknown): error is Error;
+}

src/is-error.ts

@@ -27,6 +27,10 @@ const getPrototypeOf = Object.getPrototypeOf;
 const ERROR_TYPE = '[object Error]';
 
 export function isError(a: unknown): a is Error {
+  if (typeof Error.isError === 'function') {
+    return Error.isError(a);
+  }
+
   if (a instanceof Error) {
     return true;
   }