Thankfully it was only a vSRX image as a test unit and not some super high impact virtual machine processing credit cards or anything. Let this be a warning to everyone who runs VMWare Fusion/Workstation/VirtualBox/etc., shut the machines down properly; as appliances they should gracefully recover, but there are NO GUARANTEES with VMs.
Now back to your regularly scheduled network outage.
When putting a VC together with four or five EX4300 switches, I have found that there are times when the configuration has all interfaces it can currently support, not just the interfaces that exist. This can be troublesome, especially for RSTP.
I’ve gotten into the habit of deleting all interfaces first, and only creating the interfaces needed:
firstname.lastname@example.org# delete interfaces
email@example.com# delete protocols rstp
firstname.lastname@example.org# wildcard range set interfaces xe-[0-1]/0/[0-47]
email@example.com# wildcard range set interfaces et-0/0/[48-49]
firstname.lastname@example.org# set protocols rstp interface all
I don’t know if anyone else has reproduced this, I’m waiting on DACs for my lab in order to reproduce and submit a patch.