bitcoinTx.js

const bitcore = require('bitcore-lib');
const Insight = require('bitcore-insight').Insight;

let insight = new Insight('testnet');

// Our private key and address
const wif = 'xBtatQED9H44gCmp6HAdmemAzU3n84H3dGkuWTKvE23JgHMW8gct';
const privateKey = new bitcore.PrivateKey(wif);
const myAddress = privateKey.toAddress();

// Address we are sending Bitcoin to
const addressTo = 'moCEHE5fJgb6yHtF9eLNnS52UQVUkHjnNm';

// Start the creating our transaction
const amount = 50000; // Sending amount must be in satoshis
const fee = 50000; // Fee is in satoshis

// Get the UTXOs of your Bitcoin address
insight.getUtxos(myAddress, (err, utxos) => {
        if(err){ 
          //Handle errors
          return err;
        }else { 
            // use the UTXOs to create transaction with bitcore Transaction object
            let tx = bitcore.Transaction();
            tx.from(utxos);
            tx.to(addressTo, amount);
            tx.change(myAddress);
            tx.fee(fee);
            tx.sign(privateKey);
            tx.serialize();
            
            // Broadcast your transaction to the Bitcoin network
            insight.broadcast(tx.toString(), (error, txid) => {
                if (error) {
                    return error;
                } else {
                  // Your Transaction Id
                    console.log(txid)
                }
            })
        }
    });

@johnworthley as told by @abel30567 in order to fix the error you have to use bitcore-lib which is configured with bitcore-insight. As fas as alternative is concerned i havent found any. The only way i can think of broadcasting a btc transacion rn is by running a full node

How are you importing bitcore? I am using const bitcore = require('../node_modules/bitcore-insight/node_modules/bitcore-lib') and seeing node_modules/bitcore-insight/node_modules/bitcore-lib/lib/util/preconditions.js:14 throw new errors.InvalidArgument(argumentName, message, docsPath); ^ Invalid Argument as an error?