Client crashes when entering incorrext passphrase on export

[emkll]

When exporting to a device and specifying a wrong passphrase, the client crashes when it receives

Steps to reproduce:

• Click on export for a file
• Ensure your USB devices works in the ideal case (e.g.: passphrase is correct)
• Attempt export again, this time with incorrect passphrase
• Observe the client exits without error

Relevant client logs:

019-11-07 09:49:53,103 - securedrop_client.logic:635(run_export_preflight_checks) INFO: Running export preflight checks
2019-11-07 09:49:53,104 - securedrop_client.export:233(run_preflight_checks) DEBUG: beginning preflight checks in thread 123350435710720
2019-11-07 09:49:53,913 - securedrop_client.export:236(run_preflight_checks) DEBUG: completed preflight checks: success
2019-11-07 09:49:53,914 - securedrop_client.gui.widgets:2012(_request_passphrase) DEBUG: requesting passphrase... 
2019-11-07 09:49:57,517 - securedrop_client.logic:655(export_file_to_usb_drive) INFO: Exporting file c4611_sample_explain.pdf
2019-11-07 09:49:57,520 - securedrop_client.export:254(send_file_to_usb_device) DEBUG: beginning export from thread 123350435710720
2019-11-07 09:49:59,937 - securedrop_client.export:259(send_file_to_usb_device) ERROR: USB_BAD_PASSPHRASE
2019-11-07 09:49:59,938 - securedrop_client.gui.widgets:2026(_update) DEBUG: updating status... 
2019-11-07 09:49:59,939 - root:52(excepthook) ERROR: Unrecoverable error
Traceback (most recent call last):
  File "/opt/venvs/securedrop-client/lib/python3.5/site-packages/securedrop_client/gui/widgets.py", line 2057, in _update_usb_export
    self._update(status)
  File "/opt/venvs/securedrop-client/lib/python3.5/site-packages/securedrop_client/gui/widgets.py", line 2034, in _update
    self.error_status_code.setText(_(status))
  File "/opt/venvs/securedrop-client/lib/python3.5/site-packages/securedrop_client/gui/__init__.py", line 162, in setText
    super().setText(html.escape(text, quote=False))
  File "/usr/lib/python3.5/html/__init__.py", line 19, in escape
    s = s.replace("&", "&") # Must be done first!
AttributeError: 'list' object has no attribute 'replace'

securedrop-export logs:

2019-11-07 09:49:57,914 - root:47(start) INFO: Starting SecureDrop Export 0.1.2
2019-11-07 09:49:57,915 - root:105(__init__) INFO: Retrieving VM configuration
2019-11-07 09:49:57,915 - root:108(__init__) INFO: pci_bus_id is 2
2019-11-07 09:49:57,915 - root:159(extract_tarball) INFO: Extracting tarball /tmp/sd-svs-ll9gsU/archive.sd-export into /tmp/tmpljhrieho
2019-11-07 09:49:57,917 - root:46(__init__) INFO: Parsing archive metadata
2019-11-07 09:49:57,917 - root:55(__init__) INFO: Exporting to device disk with encryption_method luks
2019-11-07 09:49:57,917 - root:64(is_valid) INFO: Validating metadata contents
2019-11-07 09:49:57,917 - root:21(__main__) INFO: Export archive is disk
2019-11-07 09:49:57,918 - root:22(__main__) INFO: Unlocking volume
2019-11-07 09:49:57,947 - root:219(unlock_luks_volume) DEBUG: Unlocking luks volume luks-d294f72d-a245-4040-8d4f-1f105e4650f8
2019-11-07 09:49:57,950 - root:226(unlock_luks_volume) DEBUG: Passing key
2019-11-07 09:49:59,989 - root:230(unlock_luks_volume) ERROR: Bad phassphrase for luks-d294f72d-a245-4040-8d4f-1f105e4650f8
2019-11-07 09:49:59,990 - securedrop_export.export:125(exit_gracefully) INFO: Exiting with message: USB_BAD_PASSPHRASE

Other information

• securedrop-client version 0.0.9-dev-20191107-060604
• securedrop-export version 0.1.2-dev-20191107-060815 (and also one built on https://github.com/freedomofpress/securedrop-export/pull/16/files)
• full disk encrypted per CLI instructions in https://github.com/freedomofpress/securedrop-export/pull/16/files as well as MBR formatted, with luks ext4 partition