Merge branch '6452-uncaught-typeerror-array_merge-argument-1-must-be-of-type-array-bool-given-in' into 'develop'

Resolve "Uncaught TypeError: array_merge(): Argument 1 must be of type array, bool given in shelluser_base_plugin.inc.php:480"

Closes #6452

See merge request ispconfig/ispconfig3!1689

Author: Till Brehm

server/lib/classes/file.inc.php

@@ -124,9 +124,11 @@ function remove_blank_lines($input, $file = 1){
 				if(trim($line) != '') $new_lines[] = $line;
 			}
 		}
-
-		$content = implode("\n", $new_lines);
-
+		if(!empty($new_lines)){
+			$content = implode("\n", $new_lines);
+		} else {
+			$content = '';
+		}
 		if($file){
 			$this->wf($input, $content);
 		} else {

server/plugins-available/shelluser_base_plugin.inc.php

@@ -477,7 +477,11 @@ private function _setup_ssh_rsa() {
 			// Remove duplicate keys
 			$existing_keys = @file($sshkeys, FILE_IGNORE_NEW_LINES);
 			$new_keys = explode("\n", $userkey);
-			$final_keys_arr = @array_merge($existing_keys, $new_keys);
+			if(is_array($existing_keys)) {
+				$final_keys_arr = @array_merge($existing_keys, $new_keys);
+			} else {
+				$final_keys_arr = $new_keys;
+			}
 			$new_final_keys_arr = array();
 			if(is_array($final_keys_arr) && !empty($final_keys_arr)){
 				foreach($final_keys_arr as $key => $val){

server/plugins-available/shelluser_jailkit_plugin.inc.php

@@ -318,6 +318,8 @@ function _setup_jailkit_chroot()
 				$options = array('hardlink');
 			} elseif ($this->jailkit_config['jailkit_hardlinks'] == 'no') {
 				$options = array();
+			} else {
+				$options = array();
 			}
 		} else {
 			$options = array('allow_hardlink');
@@ -527,7 +529,11 @@ private function _setup_ssh_rsa() {
 			// Remove duplicate keys
 			$existing_keys = @file($sshkeys, FILE_IGNORE_NEW_LINES);
 			$new_keys = explode("\n", $userkey);
-			$final_keys_arr = @array_merge($existing_keys, $new_keys);
+			if(is_array($existing_keys)) {
+				$final_keys_arr = @array_merge($existing_keys, $new_keys);
+			} else {
+				$final_keys_arr = $new_keys;
+			}
 			$new_final_keys_arr = array();
 			if(is_array($final_keys_arr) && !empty($final_keys_arr)){
 				foreach($final_keys_arr as $key => $val){