Protect partial uses of maximum with NonEmpty.

1 files changed, 3 insertions, 6 deletions

diff --git a/src/Text/Pandoc/Writers/Markdown/Inline.hs b/src/Text/Pandoc/Writers/Markdown/Inline.hs
index 19157701e..e35e1a0b9 100644
--- a/src/Text/Pandoc/Writers/Markdown/Inline.hs
+++ b/src/Text/Pandoc/Writers/Markdown/Inline.hs
@@ -17,6 +17,7 @@ import Control.Monad.Reader
 import Control.Monad.State.Strict
 import Data.Char (isAlphaNum, isDigit)
 import Data.List (find, intersperse)
+import Data.List.NonEmpty (nonEmpty)
 import qualified Data.Map as M
 import Data.Maybe (fromMaybe)
 import Data.Text (Text)
@@ -383,9 +384,7 @@ inlineToMarkdown opts (Quoted DoubleQuote lst) = do
                    else "“" <> contents <> "”"
 inlineToMarkdown opts (Code attr str) = do
   let tickGroups = filter (T.any (== '`')) $ T.group str
-  let longest    = if null tickGroups
-                     then 0
-                     else maximum $ map T.length tickGroups
+  let longest    = maybe 0 maximum $ nonEmpty $ map T.length tickGroups
   let marker     = T.replicate (longest + 1) "`"
   let spacer     = if longest == 0 then "" else " "
   let attrs      = if isEnabled Ext_inline_code_attributes opts && attr /= nullAttr
@@ -438,9 +437,7 @@ inlineToMarkdown opts (Math DisplayMath str) =
             (texMathToInlines DisplayMath str >>= inlineListToMarkdown opts)
 inlineToMarkdown opts il@(RawInline f str) = do
   let tickGroups = filter (T.any (== '`')) $ T.group str
-  let numticks   = if null tickGroups
-                     then 1
-                     else 1 + maximum (map T.length tickGroups)
+  let numticks   = 1 + maybe 0 maximum (nonEmpty (map T.length tickGroups))
   variant <- asks envVariant
   let Format fmt = f
   let rawAttribInline = return $