Add Forbidden error details

src/Endpoint/Create.php

@@ -33,7 +33,10 @@ class Create
         $schema = $resourceType->getSchema();
 
         if (! evaluate($schema->isCreatable(), [$context])) {
-            throw new ForbiddenException();
+            throw new ForbiddenException(sprintf(
+                'Cannot create resource type %s',
+                $resourceType->getType()
+            ));
         }
 
         $model = $this->newModel($resourceType, $context);

src/Endpoint/Delete.php

@@ -30,7 +30,11 @@ class Delete
         $schema = $resourceType->getSchema();
 
         if (! evaluate($schema->isDeletable(), [$model, $context])) {
-            throw new ForbiddenException();
+            throw new ForbiddenException(sprintf(
+                'Cannot delete resource %s:%s',
+                $resourceType->getType(),
+                $resourceType->getAdapter()->getId($model)
+            ));
         }
 
         run_callbacks($schema->getListeners('deleting'), [&$model, $context]);

src/Endpoint/Index.php

@@ -40,7 +40,10 @@ class Index
         $schema = $resourceType->getSchema();
 
         if (! evaluate($schema->isListable(), [$context])) {
-            throw new ForbiddenException();
+            throw new ForbiddenException(sprintf(
+                'Cannot list resource type %s',
+                $resourceType->getType()
+            ));
         }
 
         $query = $adapter->query();

src/Endpoint/Update.php

@@ -31,7 +31,11 @@ class Update
         $schema = $resourceType->getSchema();
 
         if (! evaluate($schema->isUpdatable(), [$model, $context])) {
-            throw new ForbiddenException();
+            throw new ForbiddenException(sprintf(
+                'Cannot update resource %s:%s',
+                $resourceType->getType(),
+                $resourceType->getAdapter()->getId($model)
+            ));
         }
 
         $data = $this->parseData($resourceType, $context->getRequest()->getParsedBody(), $model);

src/Exception/ForbiddenException.php

@@ -22,7 +22,8 @@ class ForbiddenException extends DomainException implements ErrorProviderInterfa
         return [
             new Error(
                 new Error\Title('Forbidden'),
-                new Error\Status($this->getJsonApiStatus())
+                new Error\Status($this->getJsonApiStatus()),
+                ...($this->message ? [new Error\Detail($this->message)] : [])
             )
         ];
     }