Crash at startup when local storage directory is not writable (eclipse-openvsx#1603)

* Fail fast at startup if local storage directory is not writable

Signed-off-by: Pranav-0440 <pranavghorpade61@gmail.com>

* Harden startup validation for local storage directory

* Use Files.isWritable to validate local storage permissions

Signed-off-by: Pranav-0440 <pranavghorpade61@gmail.com>

* Remove duplicate Java settings in VS Code

* Fix JSON formatting in settings.json

* Update settings.json

* Fix duplicate import in LocalStorageService

Removed duplicate import of jakarta.annotation.PostConstruct.

* simplify logic

---------

Signed-off-by: Pranav-0440 <pranavghorpade61@gmail.com>
Co-authored-by: Thomas Neidhart <thomas.neidhart@eclipse-foundation.org>

Author: Pranav-0440

server/src/main/java/org/eclipse/openvsx/storage/LocalStorageService.java

@@ -9,6 +9,16 @@
  * ****************************************************************************** */
 package org.eclipse.openvsx.storage;
 
+import java.io.IOException;
+import java.net.URI;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.StandardCopyOption;
+import java.util.ArrayList;
+import java.util.List;
+
+import jakarta.annotation.PostConstruct;
+
 import org.apache.commons.lang3.StringUtils;
 import org.eclipse.openvsx.entities.FileResource;
 import org.eclipse.openvsx.entities.Namespace;
@@ -22,14 +32,6 @@
 import org.springframework.web.server.ServerErrorException;
 import org.springframework.web.servlet.mvc.method.annotation.StreamingResponseBody;
 
-import java.io.IOException;
-import java.net.URI;
-import java.nio.file.Files;
-import java.nio.file.Path;
-import java.nio.file.StandardCopyOption;
-import java.util.ArrayList;
-import java.util.List;
-
 @Component
 public class LocalStorageService implements IStorageService {
 
@@ -40,6 +42,27 @@ public class LocalStorageService implements IStorageService {
     public boolean isEnabled() {
         return !StringUtils.isEmpty(storageDirectory);
     }
+    
+    @PostConstruct
+    public void validateStorageDirectory() throws IOException {
+        if (!isEnabled()) {
+            return;
+        }
+
+        var storageDirectoryPath = Path.of(storageDirectory).toAbsolutePath();
+
+        if (!Files.exists(storageDirectoryPath)) {
+            Files.createDirectories(storageDirectoryPath);
+        }
+
+        if (!Files.isDirectory(storageDirectoryPath)) {
+            throw new IllegalStateException("Local storage directory '" + storageDirectory + "' is not a directory");
+        }
+
+        if (!Files.isWritable(storageDirectoryPath)) {
+            throw new IllegalStateException("Local storage directory '" + storageDirectory + "' is not writable");
+        }
+    }
 
     @Override
     public void uploadFile(TempFile tempFile) {