Thanks Ben,

For the warning messages, would be nice to have advanced options for production product, where the developer (with enough experience on that kind of data) can establish that for less than 20 the warning is hidden.

For example, I am running stan in parallel for many data sets (for particular reason)

What the end user sees in R is

```
Exception thrown at line 28: neg_binomial_2_lpmf: Precision parameter is inf, but must be finite! 1
Exception thrown at line 29: neg_binomial_2_lpmf: Location parameter is inf, but must be finite! 1
When a numerical problem occurs, the Hamiltonian proposal gets rejected.
See http://mc-stan.org/misc/warnings.html#exception-hamiltonian-proposal-rejected
If the number in the 'count' column is small, there is no need to ask about this message on stan-users.
The following numerical problems occurred the indicated number of times on chain 1
count
Exception thrown at line 28: neg_binomial_2_lpmf: Precision parameter is inf, but must be finite! 1
Exception thrown at line 29: neg_binomial_2_lpmf: Location parameter is 0, but must be > 0! 1
When a numerical problem occurs, the Hamiltonian proposal gets rejected.
See http://mc-stan.org/misc/warnings.html#exception-hamiltonian-proposal-rejected
If the number in the 'count' column is small, there is no need to ask about this message on stan-users.
The following numerical problems occurred the indicated number of times on chain 2
count
Exception thrown at line 29: neg_binomial_2_lpmf: Location parameter is inf, but must be finite! 1
When a numerical problem occurs, the Hamiltonian proposal gets rejected.
See http://mc-stan.org/misc/warnings.html#exception-hamiltonian-proposal-rejected
If the number in the 'count' column is small, there is no need to ask about this message on stan-users.
The following numerical problems occurred the indicated number of times on chain 2
count
Exception thrown at line 28: neg_binomial_2_lpmf: Precision parameter is inf, but must be finite! 1
Exception thrown at line 29: neg_binomial_2_lpmf: Location parameter is inf, but must be finite! 1
When a numerical problem occurs, the Hamiltonian proposal gets rejected.
See http://mc-stan.org/misc/warnings.html#exception-hamiltonian-proposal-rejected
If the number in the 'count' column is small, there is no need to ask about this message on stan-users.
The following numerical problems occurred the indicated number of times on chain 2
count
Exception thrown at line 28: neg_binomial_2_lpmf: Precision parameter is inf, but must be finite! 1
When a numerical problem occurs, the Hamiltonian proposal gets rejected.
See http://mc-stan.org/misc/warnings.html#exception-hamiltonian-proposal-rejected
If the number in the 'count' column is small, there is no need to ask about this message on stan-users.
The following numerical problems occurred the indicated number of times on chain 2
count
Exception thrown at line 29: neg_binomial_2_lpmf: Location parameter is 0, but must be > 0! 1
When a numerical problem occurs, the Hamiltonian proposal gets rejected.
See http://mc-stan.org/misc/warnings.html#exception-hamiltonian-proposal-rejected
If the number in the 'count' column is small, there is no need to ask about this message on stan-users.
The following numerical problems occurred the indicated number of times on chain 2
count
Exception thrown at line 29: neg_binomial_2_lpmf: Location parameter is inf, but must be finite! 1
When a numerical problem occurs, the Hamiltonian proposal gets rejected.
See http://mc-stan.org/misc/warnings.html#exception-hamiltonian-proposal-rejected
If the number in the 'count' column is small, there is no need to ask about this message on stan-users.
The following numerical problems occurred the indicated number of times on chain 3
count
Exception thrown at line 29: neg_binomial_2_lpmf: Location parameter is 0, but must be > 0! 1
When a numerical problem occurs, the Hamiltonian proposal gets rejected.
See http://mc-stan.org/misc/warnings.html#exception-hamiltonian-proposal-rejected
If the number in the 'count' column is small, there is no need to ask about this message on stan-users.
The following numerical problems occurred the indicated number of times on chain 1
count
Exception thrown at line 29: neg_binomial_2_lpmf: Location parameter is 0, but must be > 0! 1
When a numerical problem occurs, the Hamiltonian proposal gets rejected.
See http://mc-stan.org/misc/warnings.html#exception-hamiltonian-proposal-rejected
If the number in the 'count' column is small, there is no need to ask about this message on stan-users.
The following numerical problems occurred the indicated number of times on chain 1
count
Exception thrown at line 28: neg_binomial_2_lpmf: Precision parameter is 0, but must be > 0! 1
When a numerical problem occurs, the Hamiltonian proposal gets rejected.
See http://mc-stan.org/misc/warnings.html#exception-hamiltonian-proposal-rejected
If the number in the 'count' column is small, there is no need to ask about this message on stan-users.
The following numerical problems occurred the indicated number of times on chain 1
count
Exception thrown at line 29: neg_binomial_2_lpmf: Location parameter is 0, but must be > 0! 1
When a numerical problem occurs, the Hamiltonian proposal gets rejected.
See http://mc-stan.org/misc/warnings.html#exception-hamiltonian-proposal-rejected
If the number in the 'count' column is small, there is no need to ask about this message on stan-users.
The following numerical problems occurred the indicated number of times on chain 3
count
Exception thrown at line 29: neg_binomial_2_lpmf: Location parameter is inf, but must be finite! 1
When a numerical problem occurs, the Hamiltonian proposal gets rejected.
See http://mc-stan.org/misc/warnings.html#exception-hamiltonian-proposal-rejected
If the number in the 'count' column is small, there is no need to ask about this message on stan-users.
The following numerical problems occurred the indicated number of times on chain 2
count
Exception thrown at line 29: neg_binomial_2_lpmf: Location parameter is 0, but must be > 0! 1
When a numerical problem occurs, the Hamiltonian proposal gets rejected.
See http://mc-stan.org/misc/warnings.html#exception-hamiltonian-proposal-rejected
If the number in the 'count' column is small, there is no need to ask about this message on stan-users.
The following numerical problems occurred the indicated number of times on chain 1
count
Exception thrown at line 29: neg_binomial_2_lpmf: Location parameter is inf, but must be finite! 1
When a numerical problem occurs, the Hamiltonian proposal gets rejected.
See http://mc-stan.org/misc/warnings.html#exception-hamiltonian-proposal-rejected
If the number in the 'count' column is small, there is no need to ask about this message on stan-users.
```

And so on.

I know that 1 chain error doesn’t mean much in my implementation but the user get thrown 100s of warning messages. And I can imagine the reaction in RStudio where an incredibly long output full of warnings get shown.

Thanks