Correctly detect new fontspec error for missing font

closes #448

DESCRIPTION

@@ -1,7 +1,7 @@
 Package: tinytex
 Type: Package
 Title: Helper Functions to Install and Maintain TeX Live, and Compile LaTeX Documents
-Version: 0.52.1
+Version: 0.52.2
 Authors@R: c(
   person("Yihui", "Xie", role = c("aut", "cre", "cph"), email = "[email protected]", comment = c(ORCID = "0000-0003-0645-5666")),
   person(given = "Posit Software, PBC", role = c("cph", "fnd")),

R/latex.R

@@ -561,6 +561,7 @@ regex_errors = function() {
   # ! I can't find file `hyph-de-1901.ec.tex'.
   # ! Package pdfx Error: No color profile sRGB_IEC61966-2-1_black_scaled.icc found
   # No file LGRcmr.fd. ! LaTeX Error: This NFSS system isn't set up properly.
+  # (fontspec)                The font "LibertinusSerif-Regular" cannot be
   list(
     font = c(
       # error messages about missing fonts (don't move the first item below, as
@@ -569,7 +570,8 @@ regex_errors = function() {
       ".*! Font [^=]+=([^ ]+).+ not loadable.*",
       '.*! .*The font "([^"]+)" cannot be found.*',
       '.*!.+ error:.+\\(file ([^)]+)\\): .*',
-      '.*Unable to find TFM file "([^"]+)".*'
+      '.*Unable to find TFM file "([^"]+)".*',
+      '.*\\(fontspec\\)\\s+The font "([^"]+)" cannot be.*'
     ),
     fd = c(
       # font definition files

tests/test-cran/test-latex.R

@@ -5,6 +5,7 @@ assert('detect_files() can detect filenames from LaTeX log', {
   (detect_files("! Font U/psy/m/n/10=psyr at 10.0pt not loadable: Metric (TFM) file not found") %==% font_ext("psyr"))
   (detect_files('! The font "FandolSong-Regular" cannot be found.') %==% font_ext("FandolSong-Regular"))
   (detect_files('!pdfTeX error: /usr/local/bin/pdflatex (file tcrm0700): Font tcrm0700 at 600 not found') %==% font_ext('tcrm0700'))
+  (detect_files('(fontspec)                The font "LibertinusSerif-Regular" cannot be') %==% font_ext('LibertinusSerif-Regular'))
 
   (length(detect_files("asdf qwer")) == 0)
   (detect_files("! LaTeX Error: File `framed.sty' not found.") %==% 'framed.sty')