Separate bibliography for articles: adendum - entries with capital letter gives an error (biblatex) [closed]

Question

This is question is actually a question to an answer from here, but since my rep is too low, I have no other option than to ask it like this. The question from that link goes like this:

I have a bibliography that mixes every reference type (mostly books and articles together). Now, I would love to be able to separate only the articles from the rest and display them under a separate bibliography subtitle, e.g. "Articles". Is this in any way possible?

someone called Zun answered the question that it is possible with biblatex, and a working example would be this:

    \documentclass{article}
\usepackage{filecontents}
\begin{filecontents}{bib.bib}
    @article{death-star,
    author       = {Bevel Lemelisk and Wilhuff Tarkin and Darth Vader and Darth Sidious},
    title        = {Death Star},
    howpublished = {Alderaan and Yavin 4},
    year         = {0 BBY}
  }
  @misc{death-star-2,
    author       = {Bevel Lemelisk and Wilhuff Tarkin and Darth Vader and Darth Sidious},
    title        = {Death Star II},
    howpublished = {Endor},
    year         = {4 ABY}
  }
  @article{abc,
    author       = {Abc, D.},
    title        = {The Letter Fantasies},
    year         = 1492,
    keywords     = {one}
  }
  @Book{efg,
    author       = {Efg, H.},
    title        = {Alphabet Soup},
    year         = 1942,
    keywords     = {two}
  }
\end{filecontents}
\usepackage[backend=biber,
%   style=authoryear, % uncomment to display author-year
]{biblatex}
\defbibfilter{other}{
  not type=article
}
%
\addbibresource{bib.bib}
\begin{document}
They first built \emph{Death Star}~\autocite{death-star}.

The design flaw was found in \autocite[Lemelisk et al., Chapter 3, p. 123][]{death-star}.

To address the flaw, they designed \emph{Death Star 2}~\autocite{death-star-2}
that featured many smaller diameter heat exhaust vents.

Read the letter fantasies \cite{abc} or stories from the a-soup \cite{efg}.
\nocite{*}
\printbibheading
\printbibliography[heading=subbibliography,title={Articles},type=article]
\printbibliography[heading=subbibliography,title={Other Sources},filter=other]
\end{document}

and this works flawlessly. As long as the entry-type is written with small letters. However, I use JabRef, and it formats my references with a capital letter, like @Online, @Book etc. In Zuns working example above, the entry @Book is with a capital letter. Try substituting @article with @Book. Suddenly it gives the error:

./untitled.tex:48: LaTeX Warning: Empty bibliography on input line 48.

Since all of my entries are with a capital letter, this is most unfortunate. Is there anything that can be done about this? Thank you for your time.