[format.parse.ctx] add comma before 'which'

Eisenwave · Eisenwave · commit f8741571eec5 · 2024-02-22T10:34:25.000+01:00
diff --git a/source/utilities.tex b/source/utilities.tex
@@ -17353,7 +17353,7 @@
 
 \pnum
 \throws
-\tcode{format_error} if \tcode{indexing_ == manual} is \tcode{true}
+\tcode{format_error} if \tcode{indexing_ == manual} is \tcode{true},
 which indicates mixing of automatic and manual argument indexing.
 
 \pnum
