Fix handling integers

[rok-cesnovar]

Summary

#538 introduced a bug that caused issues reported on Discourse (https://discourse.mc-stan.org/t/mismatch-in-number-of-dimensions-declared-and-found/24599). This PR fixes that bug.

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

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/)

[codecov-commenter]

Codecov Report

Merging #563 (0b5aea6) into master (ea5bc44) will decrease coverage by 1.75%.
The diff coverage is 100.00%.

❗ Current head 0b5aea6 differs from pull request most recent head 11f2585. Consider uploading reports for the commit 11f2585 to get more accurate results

@@            Coverage Diff             @@
##           master     #563      +/-   ##
==========================================
- Coverage   92.98%   91.22%   -1.76%     
==========================================
  Files          12       12              
  Lines        3191     3191              
==========================================
- Hits         2967     2911      -56     
- Misses        224      280      +56     

Impacted Files	Coverage Δ
R/data.R	99.35% <100.00%> (ø)
R/install.R	57.56% <0.00%> (-12.47%)	⬇️
R/utils.R	88.88% <0.00%> (-1.39%)	⬇️
R/model.R	92.03% <0.00%> (-0.93%)	⬇️
R/csv.R	97.76% <0.00%> (-0.90%)	⬇️
R/run.R	95.23% <0.00%> (-0.50%)	⬇️

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[jgabry]

Thanks! Merging now