[Tex/LaTex] Nested enumerate lists and missing \item errors

Question

When using nested enumerate environments, I am using the following syntax :

\documentclass{article}

\usepackage{enumitem}

\begin{document}
\begin{enumerate}[label*=\arabic*.]
\item A question
\stepcounter{enumi}
\begin{enumerate}[label*=\alph*.]
\item A subquestion.
\item Another subquestion.
\end{enumerate}
\end{enumerate}

\end{document}

which works just fine and displays exactly what I expect:

However, with this other example,

\documentclass{article}

\usepackage{enumitem}

\begin{document}
\begin{enumerate}[label*=\arabic*.]
\stepcounter{enumi}
\begin{enumerate}[label*=\alph*.]
\item A subquestion.
\item Another subquestion.
\end{enumerate}
\end{enumerate}

\end{document}

I have a missing \item error, despite of an output corresponding to my expectations.
What would be a correct way of proceeding in order to avoid such errors ?

And a related question (which would maybe deserve another topic): with TeXstudio, the second example does not display the PDF preview because of the compilation error, while with TeXmaker it does. Is there any way to display the PDF in case of (minor) compilation errors in TeXstudio ?

Answer 1

With a simple dummy item of no label \item[] {}, one can write this:

\documentclass{article}

\usepackage{enumitem}

\begin{document}

Some text ...    
\begin{enumerate}[label*=\arabic*.]
\item[] {}
\stepcounter{enumi}
\begin{enumerate}[label*=\alph*.]
\item A subquestion.
\item Another subquestion.
\end{enumerate}
\end{enumerate}
\end{document}