cpp.kak: tweak cpp-alternative-file implementation

rc/cpp.kak

@@ -91,7 +91,7 @@ def cpp-alternative-file -docstring "Jump to the alternate file (header/implemen
     dir=$(dirname ${kak_buffile})
 
     case ${file} in
-         *.c|*.cc|*.cpp|*.cxx|*.C)
+        *.c|*.cc|*.cpp|*.cxx|*.C|*.inl)
             for alt_dir in ${alt_dirs}; do
                 for ext in h hh hpp hxx H; do
                     altname="${dir}/${alt_dir}/${file%.*}.${ext}"
@@ -109,6 +109,10 @@ def cpp-alternative-file -docstring "Jump to the alternate file (header/implemen
                 [ -f ${altname} ] && break
             done
         ;;
+        *)
+            echo "'extension not recognized'"
+            exit
+        ;;
     esac
     if [ -f ${altname} ]; then
        echo edit "'${altname}'"