DOCS-1399 aggregate helper method throws exception upon error

source/core/aggregation.txt

@@ -166,8 +166,9 @@ The aggregation operation in the previous section returns a
 
 - ``result`` which holds an array of documents returned by the :term:`pipeline`
 
-- ``ok`` which holds the value ``1``, indicating success, or another value
-  if there was an error
+- ``ok`` which holds the value ``1``, indicating success.
+
+.. include:: /includes/fact-agg-helper-exception.rst
 
 As a document, the result is subject to the :ref:`BSON
 Document size <limit-bson-document-size>` limit, which is currently 16 megabytes.

source/includes/fact-agg-helper-exception.rst

@@ -0,0 +1,5 @@
+.. versionchanged:: 2.4
+   If an error occurs, the :method:`~db.collection.aggregate()` helper
+   throws an exception. In previous versions, the helper returned a
+   document with the error message and code, and ``ok`` status field
+   not equal to ``1``, same as the :dbcommand:`aggregate` command.

source/reference/command/aggregate.txt

@@ -55,6 +55,8 @@ aggregate
         } }
       );
 
+   .. include:: /includes/fact-agg-helper-exception.rst
+
    For more aggregation documentation, please see:
 
    - :doc:`/core/aggregation`

source/reference/method/db.collection.aggregate.txt

@@ -6,7 +6,7 @@ db.collection.aggregate()
 
 .. method:: db.collection.aggregate(pipeline)
 
-   .. versionadded:: 2.1.0
+   .. versionadded:: 2.2
 
    Always call the :method:`db.collection.aggregate()` method on a collection
    object.
@@ -16,6 +16,16 @@ db.collection.aggregate()
                        </reference/aggregation>` for documentation of
                        these operators.
 
+   :returns: A document with two fields:
+
+             - ``result`` which holds an array of documents returned by
+               the :term:`pipeline`
+
+             - ``ok`` which holds the value ``1``, indicating success.
+
+   :throws exception: 
+           .. include:: /includes/fact-agg-helper-exception.rst
+
    Consider the following example from the :doc:`aggregation
    documentation </core/aggregation>`.