fix: Multiplate report generation fails for different subsets of analytes

[Fersoil]

Checklist

• I added a very descriptive title to this issue.
• I used the GitHub search to find a similar question and didn't find it.
• I am sure that this is a bug in SerolyzeR package rather than my code.
• The bug is not resolved by updating to the latest stable version of SerolyzeR package.
• I included a link to the documentation page I am referring to (if applicable).

Reproduction steps

The following code fails if plates have inconsistent analyte names subsets

generate_levey_jennings_report(plates, report_title = "Levey-Jennings report")

Error Message and Stack Trace (if applicable)

Generating report... For large reports with more than 30 plates, this will take a few minutes.
Error in plot_standard_curve_stacked():
! FLU_FluA not found in one of the plate on list_of_plates
Backtrace:

1. base::print(...)
2. SerolyzeR::plot_standard_curve_stacked(...)

OS

No response