Gather error when less than two repeats are present

I was wondering whether we could change the behavior with this Error:

https://github.com/OpenFreeEnergy/openfe/blob/35a999907e6c3567e8173e8ef3ad11cf0b5785f4/openfecli/commands/gather.py#L494
I've been running into this error during benchmarking. I would like to get a preliminary result while other calculations are still running. I think what's confusing to me was that I would have expected the --allow-partial flag to handle this differently; to skip edges when only one leg is present instead of giving an error.

I wonder how many people will run multiple repeats of openfe in production, so I think long term supporting single repeats will be important. I'm not sure which would be the best way to do that, I know it's tricky because of using the standard deviation as error vs picking an analytical for a single repeat. I thought I'd just raise it here to maybe collect some ideas on that?

Start in openfecli/commands/gather.py around line 494 and inspect how the error and --allow-partial are handled. Clarify the intended behavior for a single repeat or an edge with one leg, then define completion as an agreed behavior that produces preliminary results without invalid error estimates.