\mathbf 仅在数学模式下允许。]在参考书目部分

Question

我遇到了以下错误，提示“\mathbf 仅在数学模式下允许。 ]”。但是，我在本节中没有找到使用 \mathbf 的任何地方。

\begin{singlespace}
    % increase penalty such that we don't break entries over pages
    % source: https://tex.stackexchange.com/a/43275
    \patchcmd{\bibsetup}{\interlinepenalty=5000}{\interlinepenalty=10000}{}{}
    
    % reduce spacing between each bibentry
    \setlength\bibitemsep{0.9\baselineskip}
    
    % don't justify-align entries: this prevents stretching out each line
    \raggedright
    \printbibliography[
    heading = none
    ]
\end{singlespace}

我正在使用 Biber，我的设置是

\usepackage[
  backend     = biber,
  doi         = true,
  hyperref    = true,
  maxbibnames = 99,
  sortlocale  = en_US,
  style       = numeric,
  bibencoding = utf8,
]{biblatex}

有人对此有什么想法吗？谢谢！