Minor refactoring for tool tasks

- Don't scan for translations on initialization in TranslationPageGenerator in order to speed up startup time of ToolsRunner
- Extract checking for null / empty array of File#listFiles into a separate method
- Move single method of RuntimeUtils into Utils class

src/test/java/tools/messages/VerifyMessagesTask.java

@@ -17,6 +17,8 @@ import java.util.Set;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 
+import static tools.utils.FileIoUtils.listFilesOrThrow;
+
 /**
  * Task to verify the keys in the messages files.
  */
@@ -124,12 +126,7 @@ public final class VerifyMessagesTask implements ToolTask {
     }
 
     private static List<File> getMessagesFiles() {
-        File folder = new File(MESSAGES_FOLDER);
-        File[] files = folder.listFiles();
-        if (files == null) {
-            throw new IllegalStateException("Could not read files from folder '" + folder.getName() + "'");
-        }
-
+        File[] files = listFilesOrThrow(new File(MESSAGES_FOLDER));
         List<File> messageFiles = new ArrayList<>();
         for (File file : files) {
             if (MESSAGE_FILE_PATTERN.matcher(file.getName()).matches()) {

src/test/java/tools/messages/translation/WriteAllExportsTask.java

@@ -8,6 +8,8 @@ import tools.utils.ToolsConstants;
 import java.io.File;
 import java.util.Scanner;
 
+import static tools.utils.FileIoUtils.listFilesOrThrow;
+
 /**
  * Task which exports all messages to a local folder.
  */
@@ -22,11 +24,7 @@ public class WriteAllExportsTask extends ExportMessagesTask {
 
     @Override
     public void execute(Scanner scanner) {
-        File[] messageFiles = new File(MESSAGES_FOLDER).listFiles();
-        if (messageFiles == null || messageFiles.length == 0) {
-            throw new IllegalStateException("Could not read messages folder");
-        }
-
+        final File[] messageFiles = listFilesOrThrow(new File(MESSAGES_FOLDER));
         final FileConfiguration defaultMessages = loadDefaultMessages();
         for (File file : messageFiles) {
             String code = file.getName().substring("messages_".length(), file.getName().length() - ".yml".length());