Looks like there is maybe an SE compatibility issue. SE has an item called "#se-delivery-cannon-package-rocket-fuel" which causes the combinator to blow up.

I assume this would be the same for any item put inside a item delivery cannon.

RuntimeError: Moon_Logic/controller.lua:MOD BUG - abbreviation for invalid signal string: #se-delivery-cannon-package-rocket-fuel

Ah yeah, signal string here use #, = and @ prefixes to tell apart item/fluid/virtual signals, and as usual it's only a matter of time until some mod clashes with even that kind of weirdness :)

I think you can work around that by unpacking the mod zip file in factorio mods dir, and editing control.lua file in there, so that this line:
local cn_sig_str_prefix = {item='#', fluid='=', virtual='@'}
...uses some other character(s) that don't conflict with SE mod.

But should probably be fixed by mod translating #item raw signal name to ##item and back, instead of expecting to exclusively use this prefix for its own purposes.

Thanks!

Looking into it, haven't found any problems with prefixes myself, I think they should be handled exactly like I mentioned above already.
But there was definitely that error message when using signals from items marked as "hidden", which is probably what that issue was about.
Should be fixed in 0.0.83. Thanks for reporting!