Regularization isssue in mc_stats.py

Created by: kastoryano

NetKet v3.0 I am running into a recurrent problem with mc_stats. Seems to be a regularization issue:

/home/ec2-user/my_app/env3/lib64/python3.7/site-packages/netket-3.0-py3.7.egg/netket/stats/mc_stats.py:160: RuntimeWarning: divide by zero encountered in true_divide
 95%|▉| 285/300 [00:39<00:01,  7.83it/s, Energy=-1.0943+0.0000j ± 0.00096 [var=1.1e-03, R_hat=/home/ec2-user/my_app/env3/lib64/python3.7/site-packages/netket-3.0-py3.7.egg/netket/stats/mc_stats.py:12: RuntimeWarning: divide by zero encountered in log10
 95%|▉| 285/300 [00:39<00:02,  7.17it/s, Energy=-1.0943+0.0000j ± 0.00096 [var=1.1e-03, R_hat=
Traceback (most recent call last):
  File "H2_test.py", line 101, in <module>
    gs.run(n_iter=300, out="test")
  File "/home/ec2-user/my_app/env3/lib64/python3.7/site-packages/netket-3.0-py3.7.egg/netket/abstract_variational_driver.py", line 234, in run
  File "/home/ec2-user/my_app/env3/lib64/python3.7/site-packages/netket-3.0-py3.7.egg/netket/stats/mc_stats.py", line 46, in __repr__
  File "/home/ec2-user/my_app/env3/lib64/python3.7/site-packages/netket-3.0-py3.7.egg/netket/stats/mc_stats.py", line 12, in _format_decimal
OverflowError: cannot convert float infinity to integer

Note: switching to show_progress=False in .run does not remove the error.