Monero Error is not defined
Please send help (My lvl: noob-grammer),

I ran into some issues earlier (which did not happen before) when creating New Wallet WASM. It seems to return a MoneroError but the problem is that I tried to catch it and says MoneroError is not defined (I think it's when it is creating a new Config as per the log file).

Just a quick question also. Does this have issues when the Library is called via Workers? I implemented workers that will handle each walletWasm opening as we are trying to open an array of wallets (which is a killer for my laptop).

Log error: 
```
ReferenceError: MoneroError is not defined
    at new MoneroWalletConfig (/home/hcpioquinto/Desktop/work_files/Monero_backup/node_modules/monero-javascript/src/main/js/wallet/model/MoneroWalletConfig.js:45:9)
    at Function.createWallet (/home/hcpioquinto/Desktop/work_files/Monero_backup/node_modules/monero-javascript/src/main/js/wallet/MoneroWalletWasm.js:176:62)
    at Object.module.exports.createWalletWasm (/home/hcpioquinto/Desktop/work_files/Monero_backup/node_modules/monero-javascript/index.js:183:87)
    at MoneroWalletsHandler.createNewWallet (/home/hcpioquinto/Desktop/work_files/Monero_backup/moneroAPIClass.js:218:38)
    at MoneroWalletsHandler.onCreateWalletRequest (/home/hcpioquinto/Desktop/work_files/Monero_backup/moneroAPIClass.js:195:18)
    at /home/hcpioquinto/Desktop/work_files/Monero_backup/moneroAPIClass.js:307:20
    at Array.forEach (<anonymous>)
    at MoneroWalletsHandler.onImportWallets (/home/hcpioquinto/Desktop/work_files/Monero_backup/moneroAPIClass.js:301:23)
    at initThread (/home/hcpioquinto/Desktop/work_files/Monero_backup/newServer.js:124:38)
    at Object.<anonymous> (/home/hcpioquinto/Desktop/work_files/Monero_backup/newServer.js:137:3)
    at Module._compile (internal/modules/cjs/loader.js:1137:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1157:10)
    at Module.load (internal/modules/cjs/loader.js:985:32)
    at Function.Module._load (internal/modules/cjs/loader.js:878:14)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:71:12)
    at MessagePort.<anonymous> (internal/main/worker_thread.js:162:24)
    at MessagePort.emit (events.js:315:20)
    at MessagePort.onmessage (internal/worker/io.js:78:8)
    at MessagePort.exports.emitMessage (internal/per_context/messageport.js:11:10)
```
