[CI] Add a check to detect tab in lua files (#3919)

.ci/check.sh

@@ -21,5 +21,12 @@ if [ "${unscaled_size_check}" ] || [ "${unscaled_size_check_geom}" ]; then
     exit 1
 fi
 
+tab_detected=$(grep -P "\\t" --include \*.lua --exclude={dateparser.lua,xml.lua} --recursive {reader,setupkoenv,datastorage}.lua frontend plugins spec || true)
+if [ "${tab_detected}" ]; then
+    echo -e "\\n${ANSI_RED}Error TAB character detected"
+    echo "${tab_detected}"
+    exit 1
+fi
+
 echo -e "\n${ANSI_GREEN}Luacheck results"
 luajit "$(which luacheck)" --no-color -q {reader,setupkoenv,datastorage}.lua frontend plugins spec