Crash when focusing conversations list in WhatsApp

[Cleversn]

I have the WhatsApp plus NVDA add-on installed. It has a command to focus the WhatsApp conversations list, alt+1. Nearly each time I press that keystroke, NVDA crashes, and the log seems to indicate a problem relating to this IBMTTS driver. I'm attaching nvda-old.log
The relevant messages in the log start at line 151.

[Mohamed00]

What library version are you using? What was the string that was last sent? At the moment the log level is too low to determine anything specific.

[Cleversn]

Hi, I'm using version 6.7.3.2 from the IBM FTP. As for the last string, it's difficult to capture, because when NVDA crashes, it does before I'm able to understand what he is talking. I recall there is an add-on to copy the last NVDA speech, maybe I can use it. I'll try it later.

[Mohamed00]

Try it with a different synth and see if you can copy it. This is probably a weird crash string that I'll have to work around.