How to avoid the 0 of "unnumbered chapter" in equations

Question

EDIT: I knew I was forgetting something! I have edited the question to show how to properly do it.

I have a koma-script book (my PhD thesis) that number its equations (and tables, figures, etc.) within chapters.

How do I deal with an unnumbered chapter (for instance, the introduction) and avoid the dumb eq. (0.1) that appears (but of course keep the nice eq. (1.1) of the following chapter)?

I have not found an easy way to do it, and the trick that I tried

\renewcommand*{\theequation}{%
  \ifnum\value{chapter}=0 %
\else
    \thechapter.
  \fi
  \arabic{equation}%
}

provides an ugly space (1. 1) that I don't see how to purge.

EDIT: It is sufficient to add a % symbol like this: \thechapter.%

MWE:

\documentclass{srcbook}
\usepackage{amsmath}
\begin{document}
    \chapter*{Unnumbered introduction}
    \begin{equation}
        a = 1
    \end{equation}
\chapter{Numbered chapter}
\begin{equation}
    b = 2
\end{equation}

\end{document}