distinguish failed jobs from not-yet-completed (#30)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: InventivetalentDev

core/src/main/java/org/mineskin/JobBatchChecker.java

@@ -3,7 +3,7 @@
 import org.mineskin.data.JobInfo;
 import org.mineskin.data.JobReference;
 import org.mineskin.data.JobStatus;
-import org.mineskin.data.NullJobReference;
+import org.mineskin.data.ListJobReferenceImpl;
 import org.mineskin.exception.MineskinException;
 import org.mineskin.options.IJobCheckOptions;
 import org.mineskin.response.JobListResponse;
@@ -185,8 +185,8 @@ private void handleStatus(Pending p, long now) {
         JobStatus status = p.jobInfo.status();
         if (status == JobStatus.FAILED) {
             // List endpoint doesn't return error details, and the result field is empty
-            // for failures — return a NullJobReference so callers still get the updated JobInfo.
-            p.future.complete(new NullJobReference(p.jobInfo));
+            // for failures — return a ListJobReferenceImpl so callers still get the updated JobInfo.
+            p.future.complete(new ListJobReferenceImpl(p.jobInfo));
             pending.remove(p.jobInfo.id());
             return;
         }

core/src/main/java/org/mineskin/data/JobInfo.java

@@ -66,6 +66,9 @@ public CompletableFuture<JobReference> waitForCompletion(MineSkinClient client)
     }
 
     public CompletableFuture<SkinResponse> getSkin(MineSkinClient client) {
+        if (status() == JobStatus.FAILED) {
+            throw new MineskinException("Job failed").withBreadcrumb(getBreadcrumb());
+        }
         if (result == null) {
             throw new MineskinException("Job is not completed yet").withBreadcrumb(getBreadcrumb());
         }

core/src/main/java/org/mineskin/data/JobReference.java

@@ -1,6 +1,7 @@
 package org.mineskin.data;
 
 import org.mineskin.MineSkinClient;
+import org.mineskin.exception.MineskinException;
 import org.mineskin.response.SkinResponse;
 
 import java.util.Optional;
@@ -12,10 +13,12 @@ public interface JobReference {
     Optional<SkinInfo> getSkin();
 
     default CompletableFuture<SkinInfo> getOrLoadSkin(MineSkinClient client) {
+        if (getJob().status() == JobStatus.FAILED) {
+            throw new MineskinException("Job failed").withBreadcrumb(getJob().getBreadcrumb());
+        }
         if (this.getSkin().isPresent()) {
             return CompletableFuture.completedFuture(this.getSkin().get());
-        } else {
-            return getJob().getSkin(client).thenApply(SkinResponse::getSkin);
         }
+        return getJob().getSkin(client).thenApply(SkinResponse::getSkin);
     }
 }

core/src/main/java/org/mineskin/data/ListJobReferenceImpl.java

@@ -0,0 +1,22 @@
+package org.mineskin.data;
+
+import java.util.Optional;
+
+public class ListJobReferenceImpl implements JobReference {
+
+    private final JobInfo job;
+
+    public ListJobReferenceImpl(JobInfo job) {
+        this.job = job;
+    }
+
+    @Override
+    public JobInfo getJob() {
+        return job;
+    }
+
+    @Override
+    public Optional<SkinInfo> getSkin() {
+        return Optional.empty();
+    }
+}

core/src/main/java/org/mineskin/response/JobResponseImpl.java

@@ -4,7 +4,9 @@
 import com.google.gson.JsonObject;
 import org.mineskin.MineSkinClient;
 import org.mineskin.data.JobInfo;
+import org.mineskin.data.JobStatus;
 import org.mineskin.data.SkinInfo;
+import org.mineskin.exception.MineSkinRequestException;
 
 import java.util.Map;
 import java.util.Optional;
@@ -31,15 +33,17 @@ public Optional<SkinInfo> getSkin() {
 
     @Override
     public CompletableFuture<SkinInfo> getOrLoadSkin(MineSkinClient client) {
+        if (getJob().status() == JobStatus.FAILED) {
+            throw new MineSkinRequestException("job_failed", "Job failed", this);
+        }
         if (this.skin != null) {
             this.skin.setBreadcrumb(getBreadcrumb());
             return CompletableFuture.completedFuture(this.skin);
-        } else {
-            return getJob().getSkin(client).thenApply(skin -> {
-                this.skin = skin.getSkin();
-                return this.skin;
-            });
         }
+        return getJob().getSkin(client).thenApply(skin -> {
+            this.skin = skin.getSkin();
+            return this.skin;
+        });
     }
 
 }