correctly export array to subscript

* fix shellcheck errors and warnings

yadm

@@ -1577,7 +1577,11 @@ function invoke_hook() {
     YADM_HOOK_FULL_COMMAND=$FULL_COMMAND
     YADM_HOOK_REPO=$YADM_REPO
     YADM_HOOK_WORK=$YADM_WORK
-    YADM_ENCRYPT_INCLUDE_FILES=${ENCRYPT_INCLUDE_FILES[@]}
+
+    # pack array to export it; filenames including a newline character (\n)
+    # are NOT supported
+    YADM_ENCRYPT_INCLUDE_FILES=$(join_string $'\n' "${ENCRYPT_INCLUDE_FILES[@]}")
+
     export YADM_HOOK_COMMAND
     export YADM_HOOK_EXIT
     export YADM_HOOK_FULL_COMMAND
@@ -1821,6 +1825,13 @@ function auto_bootstrap() {
 
 }
 
+# ****** Helper Functions ******
+
+function join_string {
+    local IFS="$1"
+    echo "${*:2}"
+}
+
 # ****** Prerequisites Functions ******
 
 function require_archive() {
@@ -1888,7 +1899,7 @@ function readlink_available() {
   return 1
 }
 
-# ****** Directory tranlations ******
+# ****** Directory translations ******
 
 function unix_path() {
   # for paths used by bash/yadm
@@ -1908,6 +1919,7 @@ function mixed_path() {
 }
 
 # ****** echo replacements ******
+
 function echo() {
   IFS=' '
   printf '%s\n' "$*"