kakrc: refactor colorscheme implementation

Style tweaks, and remove check for parameter count as this is already
done by Kakoune itself (the command is specified to take 1 parameter)

share/kak/kakrc

@@ -1,29 +1,27 @@
 def -params 1 -docstring "colorscheme <name>: enable named colorscheme" \
     -shell-candidates %{
     find -L "${kak_runtime}/colors" "${kak_config}/colors" -type f -name '*\.kak' \
-        | while read -r path_colorscheme; do
+        | while read -r filename; do
-            basename="${path_colorscheme##*/}"
+            basename="${filename##*/}"
             printf %s\\n "${basename%.*}"
         done | sort -u
   } \
   colorscheme %{ %sh{
     find_colorscheme() {
-        find -L "${1}" -type f -name "${2}\\.kak" | head -n 1
+        find -L "${1}" -type f -name "${2}".kak | head -n 1
     }
 
-    if [ $# -lt 1 ]; then
+    if [ -d "${kak_config}/colors" ]; then
-        echo "echo -markup '{Error}Usage: colorscheme <scheme name>'"
+        filename=$(find_colorscheme "${kak_config}/colors" "${1}")
-    else
+    fi
-        path_colorscheme=$(find_colorscheme "${kak_config}/colors" "${1}")
+    if [ -z "${filename}" ]; then
-        if [ -z "${path_colorscheme}" ];then
+        filename=$(find_colorscheme "${kak_runtime}/colors" "${1}")
-            path_colorscheme=$(find_colorscheme "${kak_runtime}/colors" "${1}")
     fi
 
-        if [ -z "${path_colorscheme}" ]; then
+    if [ -n "${filename}" ]; then
-            echo "echo -markup '{Error}No such colorscheme'"
+        printf 'source %%{%s}' "${filename}"
     else
-            printf 'source %%{%s}' "${path_colorscheme}"
+        echo "echo -markup '{Error}No such colorscheme'"
-        fi
     fi
 }}