Fix error message for the old interface.

[tobiasraabe]

Closes #39.

[codecov]

Codecov Report

Merging #40 (923a666) into main (bbed260) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main      #40   +/-   ##
=======================================
  Coverage   99.83%   99.83%           
=======================================
  Files          17       17           
  Lines         622      623    +1     
=======================================
+ Hits          621      622    +1     
  Misses          1        1           

Flag	Coverage Δ
end_to_end	98.07% <100.00%> (+<0.01%)	⬆️
unit	48.79% <60.00%> (+0.08%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/pytask_latex/collect.py	99.01% <ø> (ø)
tests/test_latex_dependency_scanner.py	100.00% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update bbed260...923a666. Read the comment docs.