catch PCH errors with informative message feature

[rok-cesnovar]

Summary

Fixes #321

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):
Rok Češnovar, Uni. of Ljubljana

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)

[codecov-io]

Codecov Report

Merging #384 (1883b49) into master (2386876) will decrease coverage by 0.06%.
The diff coverage is 50.00%.

@@            Coverage Diff             @@
##           master     #384      +/-   ##
==========================================
- Coverage   90.25%   90.19%   -0.07%     
==========================================
  Files          12       12              
  Lines        2616     2620       +4     
==========================================
+ Hits         2361     2363       +2     
- Misses        255      257       +2     

Impacted Files	Coverage Δ
R/model.R	89.45% <50.00%> (-0.44%)	⬇️

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[jgabry]

Thanks! In general I think grepl(..., fixed=TRUE) is nicer that regexpr(..., fixed=TRUE) > 0, but it doesn't really matter. And we already use the latter already in multiple places in the codebase, so no big deal.

[rok-cesnovar]

Didn know that one(grepl vs regepxr). Is it worth it to open an issue to unify?

[jgabry]

Didn know that one(grepl vs regepxr). Is it worth it to open an issue to unify?

Yeah grepl returns T/F, so that's pretty useful. Definitely not a big deal, but could be nice to unify next time one of us is looking for an easy issue to close ;)

[jgabry]

Passing all checks so will merge now. I also opened #385 about the grepl vs regexpr.