fix: link launch dir with existing nucleus package if does not exist

src/main/java/com/aws/greengrass/lifecyclemanager/KernelAlternatives.java

@@ -170,8 +170,19 @@ public boolean isLaunchDirSetup() {
      */
     public void validateLaunchDirSetupVerbose() throws DirectoryValidationException, DeploymentException {
         Path currentDir = getCurrentDir();
-        if (!Files.isSymbolicLink(currentDir)) {
-            throw new DirectoryValidationException("Missing symlink to current nucleus launch directory");
+        if (!Files.isSymbolicLink(getCurrentDir())) {
+            try {
+                /*
+                Simply recreating a new init dir and relinking the current Nucleus jar path to it should be
+                sufficient as the kernel update workflow will create the new launch dir and its links anyway
+                 */
+                relinkInitLaunchDir(locateCurrentKernelUnpackDir(), true);
+            } catch (IOException ex) {
+                throw new DirectoryValidationException("Unable to relink init launch directory", ex);
+            } catch (URISyntaxException ex) {
+                // TODO: Fix usage of root path with spaces on linux
+                throw new DeploymentException("Unable to relink init launch directory", ex);
+            }
         }
         Path loaderPath = getLoaderPathFromLaunchDir(currentDir);
         if (Files.exists(loaderPath)) {

src/main/java/com/aws/greengrass/lifecyclemanager/exceptions/DirectoryValidationException.java

@@ -15,4 +15,9 @@ public DirectoryValidationException(String message) {
         super(message);
         super.addErrorCode(DeploymentErrorCode.LAUNCH_DIRECTORY_CORRUPTED);
     }
+
+    public DirectoryValidationException(String message, Throwable throwable) {
+        super(message, throwable);
+        super.addErrorCode(DeploymentErrorCode.LAUNCH_DIRECTORY_CORRUPTED);
+    }
 }