1 file changed, 7 insertions, 2 deletions
diff --git a/custom/extensions/syntax-highlight.lua b/custom/extensions/syntax-highlight.lua
index 7414b63..2928250 100644
--- a/custom/extensions/syntax-highlight.lua
+++ b/custom/extensions/syntax-highlight.lua
@@ -4,8 +4,8 @@
 -- Scintillua lexers and reach the page wrapped in span elements carrying the
 -- hl- classes that assets/cgit.css styles. Whenever a piece is missing or
 -- will not load, from lpeg down to a single lexer, the filter falls back to
--- plain escaped text instead of failing. It runs on Lua 5.1 through 5.5 and
--- LuaJIT.
+-- plain escaped text instead of failing, and a missing lpeg or Scintillua is
+-- noted in the error log. It runs on Lua 5.1 through 5.5 and LuaJIT.
 --
 --     source-filter=lua:/usr/local/lib/cgit/filters/syntax-highlight.lua
 
@@ -140,6 +140,7 @@ end
 local function load_scintillua()
 	local dir = scintillua_path()
 	if not dir then
+		io.stderr:write("[cgit] Unable to find the Scintillua lexers, so source is shown uncoloured\n")
 		return nil
 	end
 	package.path = dir .. "/?.lua;" .. package.path
@@ -149,6 +150,10 @@ local function load_scintillua()
 	if ok and type(mod) == "table" and type(mod.load) == "function" then
 		return mod
 	end
+	if not ok then
+		local reason = tostring(mod):match("[^\n]*")
+		io.stderr:write("[cgit] Unable to load the Scintillua lexers: " .. reason .. "\n")
+	end
 	return nil
 end