Better handling of emtpy string input

[lorenzwalthert]

Closes #884.

[codecov-commenter]

Codecov Report

Merging #885 (027c8a0) into main (be6449c) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #885      +/-   ##
==========================================
+ Coverage   89.65%   89.67%   +0.01%     
==========================================
  Files          47       47              
  Lines        2514     2518       +4     
==========================================
+ Hits         2254     2258       +4     
  Misses        260      260              

Impacted Files	Coverage Δ
R/roxygen-examples.R	98.43% <100.00%> (+0.05%)	⬆️
R/transform-files.R	97.05% <100.00%> (+0.04%)	⬆️

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[github-actions]

This is how benchmark results would change (along with a 95% confidence interval in relative change) if 1e52a36 is merged into main:

•   :ballot_box_with_check:cache_applying: 31ms -> 31ms [-1.77%, +1.39%]
•   :ballot_box_with_check:cache_recording: 1.11s -> 1.11s [-1.81%, +0.69%]
•   :ballot_box_with_check:without_cache: 2.94s -> 2.95s [-0.63%, +1.35%]

Further explanation regarding interpretation and methodology can be found in the documentation.

[github-actions]

This is how benchmark results would change (along with a 95% confidence interval in relative change) if 0d1ccbe is merged into main:

•   :ballot_box_with_check:cache_applying: 33.3ms -> 33.3ms [-3%, +3.04%]
•   :ballot_box_with_check:cache_recording: 1.35s -> 1.35s [-1.63%, +2.03%]
•   :ballot_box_with_check:without_cache: 3.58s -> 3.6s [-0.89%, +2.03%]

Further explanation regarding interpretation and methodology can be found in the documentation.

[github-actions]

This is how benchmark results would change (along with a 95% confidence interval in relative change) if b2d82ea is merged into main:

•   :ballot_box_with_check:cache_applying: 32.5ms -> 32.3ms [-1.19%, +0.51%]
•   :ballot_box_with_check:cache_recording: 1.16s -> 1.16s [-0.87%, +0.68%]
•   :ballot_box_with_check:without_cache: 3.1s -> 3.1s [-0.4%, +0.82%]

Further explanation regarding interpretation and methodology can be found in the documentation.