Compilation errors when changing the thesis type to "seminar"

[FabianB98]

When changing the thesis type to seminar (and changing nothing else within the cloned repo), a lot of compilation errors are thrown both on Overleaf as well as on my local TeX Live installation.

While these errors can be avoided by neither including the "How to Use" section nor the appendix (i.e. removing or commenting out lines 115 and 136 of thesis.tex), this is not an ideal solution for two reasons: First, it is not yet documented that this workaround can resolve the compilation errors, meaning that one has to figure this out by either knowing how to understand the underlying cause of LaTeX compilation errors or by trial and error. However, the more important reason why this workaround is not ideal is the fact that one can't use the appendix with thesis type seminar (as far as I understand the contents of KITthesis.cls, this issue should also arise for thesis type techreport) as the underlying document class scrartcl doesn't support chapters natively which results in the following compilation error to be thrown when trying to include the appendix:

\caption@appendix@ORI ->\par \chaptermark 
                                          {\appendixname } \setcounter {sect...
l.6 \label
          {ch:Appendix}
The control sequence at the end of the top line
of your error message was never \def'ed. If you have
misspelled it (e.g., `\hobx'), type `I' and the correct
spelling (e.g., `I\hbox'). Otherwise just continue,
and I'll forget about whatever was undefined.

As far as I understand this error, it seems to be caused by the redefinition of the \appendix command in lines 198 to 205 of KITthesis.cls. More precisely, it seems to originate from line 199 (\chaptermark{\appendixname}) because if I remove said line 199, the template compiles again without any errors. However, as I don't know that much about document class definitions, I'm unable to propose a solution which avoids completely removing that line of code.