Fixes #2568. Updates the code so on exception in generated quantities, all generated quantities are NaN

[syclik]

Submission Checklist

• Run unit tests: ./runTests.py src/test/unit
• Run cpplint: make cpplint
• Declare copyright holder and open-source license: see below

Summary

Fixes the behavior in mcmc_writer so that when there's an exception thrown in the model's generated quantities block, it writes out the parameter values and NaN for any generated quantity.

Intended Effect

Changes the behavior so that the number of draws is the number of iterations.

How to Verify

There's an updated unit test that verifies that the right terms are NaN.

If you run the model in issue #2568, there are now the right number of posterior draws with the rejections forcing all of the generated quantities to output NaN.

Side Effects

This fixes weird behavior of differing chain lengths.

This may affect the interfaces if they aren't accepting NaN as a valid value.

Documentation

None.

Copyright and Licensing

Please list the copyright holder for the work you are submitting (this will be you or your assignee, such as a university or company):

Generable

By submitting this pull request, the copyright holder is agreeing to license the submitted work under the following licenses:

• Code: BSD 3-clause (https://opensource.org/licenses/BSD-3-Clause)
• Documentation: CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

[seantalts]

Looks good to me. Not sure if you want someone else to double check.