[MM-59825] Fix linter error found by updated govet (#27715)

server/channels/app/integration_action_test.go

@@ -167,7 +167,7 @@ func TestPostActionEmptyResponse(t *testing.T) {
 		})
 
 		_, err = th.App.DoPostActionWithCookie(th.Context, post.Id, attachments[0].Actions[0].Id, th.BasicUser.Id, "", nil)
-		require.Error(t, err)
+		require.NotNil(t, err)
 		assert.Contains(t, err.DetailedError, "context deadline exceeded")
 	})
 }