docs: Signer for process spawning generates error if Arweave wallet is not installed

[hitwill]

The signer specified here needs Arweave wallet installed

import { createDataItemSigner, spawn } from "@permaweb/ao-sdk";

const processId = await spawn({
  // The Arweave TXID of the ao Module
  module: "module TXID",
  // The Arweave wallet address of a Scheduler Unit
  scheduler: "_GQ33BkPtZrqxA84vM8Zk-N2aO0toNNu_C-l-rawrBA",
  // A signer function containing your wallet
  signer: createDataItemSigner(globalThis.arweaveWallet),
  /*
    Refer to a Processes' source code or documentation
    for tags that may effect its computation.
  */
  tags: [
    { name: "Your-Tag-Name-Here", value: "your-tag-value" },
    { name: "Another-Tag", value: "another-value" },
  ],
});

However, some browser applications might not need Arweave wallet specifically. E.g.

1. They might authenticate the user in some other way
2. They might be trivial tasks that do not need the extra UX burden of installing / signing a wallet

In this case, a custom signer can be used as bellow:

// eslint-disable-next-line @typescript-eslint/ban-ts-comment
//@ts-nocheck

import * as WarpArBundles from 'warp-arbundles';
const pkg = WarpArBundles.default ? WarpArBundles.default : WarpArBundles;
const { createData, ArweaveSigner } = pkg;

export function createDataItemSigner(wallet) {
  const signer = async ({ data, tags, target, anchor }) => {
    const signer = new ArweaveSigner(wallet);
    const dataItem = createData(data, signer, { tags, target, anchor });
    return dataItem.sign(signer).then(async () => ({
      id: await dataItem.id,
      raw: await dataItem.getRaw(),
    }));
  };

  return signer;
}