Calf pitch tools crashes ardour

[RohanM]

I have an ardour session using Calf pitch tools and reverb. When I attempt to import a wav file and preview a sound from the import dialogue, ardour crashes. If I remove pitch tools from the two tracks it's on, restart ardour and try again, ardour doesn't crash.

I'm running Ubuntu 20.04 with the stock calf-plugins package at version 0.90.3-1build2, with Ardour 6.2.0.

Reproduction

1. Download this session: http://rohanmitchell.com/random/ardour-crash-session-20200714.tgz
2. There are two snapshots, included; open the "riffing on beats" snapshot
3. Press ctrl-i to open the import dialogue
4. Click on a wav file, or with autoplay disabled, click on a wav file then click play
5. Ardour crashes