Oh Sorry, I misread your post. Then it seems even more likely that you have some memory corruption bug. Unfortunately, enabling the address sanitizer will only work if the host was also compiled with the address sanitizer enabled. So you can’t use the address sanitizer and then test your plug-in in GarageBand.
However, it’s worth a try building your AU with the address sanitizer enabled and then also building JUCE’s plugin host with address sanitizer enabled. Then host your plug-in with the JUCE audio plug-in host.
Even if the crash normally does not happen in the JUCE audio plugin host, many memory corruption bugs will not always trigger a crash in all circumstances (for example, your plug-in works in Logic Pro). Nevertheless, the address sanitizer will still pick up any use-after free or out-of-bounds memory bugs.