I attach log and the script which caused this. Parts of the editor still work, but the game clock ceases to count. The map consists of one PRPL Core running that script (well, I was actually looking for a bug in my PRPL for a while before I realised that the game clock was frozen, but the particle-based bits haven't changed significantly).
The original thought was to create a bound particle shape from prespecified coordinates.
Having just broken something else in a similar manner, I'll hazard that this is caused by a particle being created off-map, then having a bond applied in the same script invocation. This seems to cause Constrain to look for the non-existent particle, resulting in an exception and a break of the main loop.
I've added this and a couple other exception topics to my TODO list. So they will get taken of here shortly.
This also seems to be able to occur when particles are edge-destroy-ed due to a bond creation (teleporting?). Observed without a script-created particle in sight.
I attach a save to reproduce it. (Bonding all particles in range every 200 frames, it may take a few iterations for the problem to appear.)