Cleanup resources when plugin startup fails (#5765)

Signed-off-by: JohnNiang <johnniang@foxmail.com>

application/src/main/java/run/halo/app/plugin/SpringPlugin.java

@@ -25,6 +25,7 @@ public class SpringPlugin extends Plugin {
 
     @Override
     public void start() {
+        try {
             // initialize context
             var pluginId = pluginContext.getName();
             this.context = contextFactory.create(pluginId);
@@ -41,28 +42,38 @@ public class SpringPlugin extends Plugin {
                 this.delegate.start();
             }
             context.publishEvent(new SpringPluginStartedEvent(this, this));
+        } catch (Throwable t) {
+            // try to stop plugin for cleaning resources if something went wrong
+            this.stop();
+            // propagate exception to invoker.
+            throw t;
+        }
     }
 
     @Override
     public void stop() {
+        try {
             if (context != null) {
                 context.publishEvent(new SpringPluginStoppingEvent(this, this));
             }
             if (this.delegate != null) {
                 this.delegate.stop();
             }
+        } finally {
             if (context instanceof ConfigurableApplicationContext configurableContext) {
                 configurableContext.close();
             }
             // reset application context
             context = null;
         }
+    }
 
     @Override
     public void delete() {
         if (delegate != null) {
             delegate.delete();
         }
+        this.delegate = null;
     }
 
     public ApplicationContext getApplicationContext() {