make \@title and \@author robust

required/latex-lab/changes.txt

@@ -1,3 +1,7 @@
+2024-01-18 Ulrike Fischer <[email protected]> 
+	* latex-lab-title.dtx: make \@title and \@author robust to avoid errors
+	if they are not set.
+
 2024-01-18 Ulrike Fischer <[email protected]> 
 	* latex-lab-block.dtx: add support to set an attribute-class for para-main.
 

required/latex-lab/latex-lab-title.dtx

@@ -16,8 +16,8 @@
 %
 % for those people who are interested or want to report an issue.
 %
-\def\ltlabtitledate{2023-12-22}
-\def\ltlabtitleversion{0.85a}
+\def\ltlabtitledate{2024-01-21}
+\def\ltlabtitleversion{0.85b}
 
 %<*driver>
 \documentclass{l3doc}
@@ -134,7 +134,7 @@
 \ProvidesExplPackage {latex-lab-testphase-title} {\ltlabtitledate} {\ltlabtitleversion}
   {Changes related to the tagging of the title}
 %    \end{macrocode}
-
+%
 % \subsection{\cs{maketitle} in article class}
 % 
 %    \begin{macrocode}
@@ -316,7 +316,12 @@
 %
 % A helper command to convert the title into a pdfstring similar to 
 % \cs{pdfstringdef}.
-%  
+% As we use \cs{text_purify} we must ensure that the default definitions
+% of \cs{@title} and \cs{@author} are robust:
+%    \begin{macrocode}
+\protected\def\@title{\@latex@error{No \noexpand\title given}\@ehc}
+\protected\def\@author{\@latex@warning@no@line{No \noexpand\author given}}
+%    \end{macrocode}
 % TODO: This should be improved and moved into the pdf module so that 
 % it is generally available.
 %    \begin{macrocode}

required/latex-lab/testfiles-title/title-empty.lvt

@@ -0,0 +1,11 @@
+\ExplSyntaxOn
+\debug_on:n { check-declarations , deprecation }
+\sys_gset_rand_seed:n{1000} 
+\ExplSyntaxOff
+\DocumentMetadata{testphase={phase-III,title},pdfversion=2.0}
+\input{regression-test}
+\documentclass{article}
+\begin{document}
+\START 
+\maketitle 
+\end{document}

required/latex-lab/testfiles-title/title-empty.tlg

@@ -0,0 +1,18 @@
+This is a generated file for the l3build validation system.
+Don't change this file in any respect.
+! LaTeX Error: No\title given.
+See the LaTeX manual or LaTeX Companion for explanation.
+Type  H <return>  for immediate help.
+ ...                                              
+l. ...\maketitle
+Try typing  <return>  to proceed.
+If that doesn't work, type  X <return>  to quit.
+LaTeX Font Info:    External font `cmex10' loaded for size
+(Font)              <12> on input line ....
+LaTeX Font Info:    External font `cmex10' loaded for size
+(Font)              <8> on input line ....
+LaTeX Font Info:    External font `cmex10' loaded for size
+(Font)              <6> on input line ....
+LaTeX Warning: No\author given.
+[1
+] (title-empty.aux)