為什麼 Babel 與 PSPicture 和 LuaLaTeX 一起使用時會發生錯誤？

Question

下面顯示的 MWE 僅在\usepackage[greek,brazilian]{babel}刪除該行後才進行編譯。

\documentclass[a4paper,10pt]{book}

\usepackage{auto-pst-pdf}
\ifpdf\else
  \usepackage{pst-electricfield}
\fi

\usepackage[greek,brazilian]{babel}

\begin{document}

\begin{pspicture}(-6,-6)(6,6)
  \psframe*[linecolor=lightgray!50](-6,-6)(6,6)
  \psgrid[subgriddiv=0,gridcolor=gray,griddots=10]
  \psElectricfield[Q={[1 0 0]},linecolor=black] 
\end{pspicture}

\end{document}

以下是該錯誤的 Latex 日誌摘錄：

File: main-pics.pdf Graphic file (type pdf)

<use main-pics.pdf, page 1>
Package pdftex.def Info: main-pics.pdf, page1 used on input line 13.
(pdftex.def)             Requested size: 571.13235pt x 572.1361pt.

Overfull \hbox (241.13235pt too wide) in paragraph at lines 13--17
[][][] 
 []

[1{/var/lib/texmf/fonts/map/pdftex/updmap/pdftex.map}


Non-PDF special ignored!
Non-PDF special ignored!
Non-PDF special ignored!<./main-pics.pdf>] (./main.aux))

Here is how much of LuaTeX's memory you used:
 10093 strings out of 494688

你知道為什麼使用 Babel 會導致這個錯誤嗎？