[Cashtab] Prevent .map error in TxHistory

Summary:
T2837

If parsedTxHistory is not an array, pass an empty array to the TxHistory component

Test Plan:
npm start
Try to recreate the error described in D12759 and the task description.
Hopefully, fail

Reviewers: #bitcoin_abc, emack

Reviewed By: #bitcoin_abc, emack

Subscribers: emack

Differential Revision: https://reviews.bitcoinabc.org/D12770