Compilation errors after importing the musixtex package

I have a problem with my LaTeX project. After I import the musixtex package, I’m suddenly getting compilation errors regarding bibliography, something that I don’t think is relevant to the musixtex package. I have created a minimum working example:

documentclass[10pt,a4paper]{article}
usepackage[backend=biber, style=iso-numeric, alldates=iso]{biblatex} 
usepackage{musixtex}
addbibresource{MyB.bib}

begin{document}
Textcite{testsource}.
printbibliography[title={Literatura}, heading=bibintoc]
end{document}

MyB.bib file:

@online{testsource,
  title = {TestSource},
  urldate = {2021-04-03},
  url = {https://stackoverflow.com/},
}

So after I import the musixtex package, I get 4 errors regarding the bibliography, two are "Missing number, treated as zero" and two are "Illegal unit of measure (pt inserted)". The document itself seems to be unaffected, but I’d rather there weren’t any compilation errors. If I remove the musixtex package, the problem disappears. Thanks for any help in advance.

documentclass[czech,bachelor]{article}
usepackage[autostyle=true,czech=quotes]{csquotes}
usepackage[backend=biber, style=iso-numeric, alldates=iso]{biblatex}
letbiblatexaddspaceaddspace
usepackage{musixtex}
addbibresource{biblatex-examples.bib}

begin{document}
Textcite{doody}.
letaddspacebiblatexaddspace
printbibliography[title={Literatura}, heading=bibintoc]
end{document}