Opening shaders in .29 and .30, and other bugs

Since .29, and into .30, some shaders I create are un-openable - using rotator node, a bunch of component masks, some custom values - I can't show you the graph, because I never get that far:

Hangs at this point.
The errors are:

With the final one building - seems like a memory thing.
Also, when I force-quit, and re-open, then this error appears.

Also, when I duplicate a node now, I get a mess of many other nodes:
BEFORE cmd.D

AFTER:

As well, I can't delete certain nodes after .30 - they just "zombie" back again:
BEFORE CMD/Delete:

AFTER (Nodes remain, are re-created in the centre of the workspace:

This is probably all due to the new undo, which I'm sure would be nice, but for now I think I prefer the stability without it.