Concat/Concat2 UGens segfault (large storesize)

[pistil-pestle]

Possibly related to #110

I'm on a OS X 11.4 (Big Sur), 8GB RAM, running SC SuperCollider 3.13.0 with the same (most recent) version of sc3-plugins.

I've noticed a reproducible issue where running the Concat or Concat2 UGens with large sample buffer sizes (storesize) causes scsynth to crash with EXC_BAD_ACCESS (SIGSEGV). This can occur with a single Concat2 instance with a large storesize, or multiple instances where the storesize is above some threshold. The threshold that causes a crash appears to depend on other factors (in particular what I'm using for Concat2's control and source, e.g. a buffer vs. something like a noise UGen).

On my machine, for example, attempting to run two Concat2 instances each with storesize > 12.0 using buffers read from files for control and source on both causes a crash.

I'd be happy to share code snippets or a full Console crash log if it would be helpful.