Version of EOSJS
eosjs@20.0.0-beta1

Describe the bug
rpc.get_code(account_name) fails with the this error message:
... Error: Returning WAST from get_code is no longer supported ...

To Reproduce

1. Execute this code:
   const eosjs = require('eosjs');
   const fetch = require('node-fetch');
   const rpc = new eosjs.Rpc.JsonRpc('http://127.0.0.1:8888', { fetch });

(async (account_name) => {
result = await rpc.get_code(account_name);
console.log(result)
})("eosio")

4. See error message:
   (node:1590) UnhandledPromiseRejectionWarning: Error: Returning WAST from get_code is no longer supported
   at new RpcError (/mnt/c/Workspaces/EOS/eosfactory/node_modules/eosjs/dist/eosjs-rpcerror.js:22:28)
   at JsonRpc. (/mnt/c/Workspaces/EOS/eosfactory/node_modules/eosjs/dist/eosjs-jsonrpc.js:117:35)
   at step (/mnt/c/Workspaces/EOS/eosfactory/node_modules/eosjs/dist/eosjs-jsonrpc.js:35:23)
   at Object.next (/mnt/c/Workspaces/EOS/eosfactory/node_modules/eosjs/dist/eosjs-jsonrpc.js:16:53)
   ..........................

Expected behavior
Obvious

Screenshots
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Desktop (please complete the following information):

• OS: [e.g. UBUNTU]
• Browser [e.g. Node]
• Version [e.g. 16]

Smartphone (please complete the following information):

• Device: [e.g. iPhone6]
• OS: [e.g. iOS8.1]
• Browser [e.g. stock browser, safari]
• Version [e.g. 22]

Additional context
Add any other context about the problem here.