Bug when sending transaction after importing wallet

Reported by @christophquill

Hi, after importing a wallet I got an error when try to send BCH:

Unexpected Application Error!

Error: [DecimalError] Invalid argument: null
    at new A (http://localhost/assets/index-fe5f35b3.js:8:211287)
    at Js (http://localhost/assets/index-fe5f35b3.js:8:215901)
    at Af (http://localhost/assets/index-fe5f35b3.js:8:216257)
    at http://localhost/assets/index-fe5f35b3.js:262:27364
    at http://Array.map (<anonymous>)
    at AV (http://localhost/assets/index-fe5f35b3.js:262:26895)
    at E0 (http://localhost/assets/index-fe5f35b3.js:6:19538)
    at rb (http://localhost/assets/index-fe5f35b3.js:8:44055)
    at ZQ (http://localhost/assets/index-fe5f35b3.js:8:39787)
    at fM (http://localhost/assets/index-fe5f35b3.js:8:39715)```

May be related to the bug fshinetop discovered. Probably addressed by #1 (closed)