Fail early when running nonsense ANOHE

[gertvv]

For example, in this network there is nothing to be gained from running an ANOHE:

MTC dataset: Network
Arm-level data:
study treatment responders sampleSize
1 STUDY1 A 35 408
2 STUDY1 B 20 347
3 STUDY1 C 19 368
4 STUDY1 D 17 371
5 STUDY2 D 18 167
6 STUDY2 E 18 167
7 STUDY2 F 19 84

And running such an analysis fails at some random point. It would be better to fail early and give a clear error message.

[mmkamso]

Hi Dr. Gert, please first of all thank you for the package GEMTC. Please wanted to ask whether you have a way to get reproducible results from the GEMTC package after running the mcmc. Thank you