Description of problem:
The crash happened when opening a link at http://nabble.documentfoundation.org/QA-f3613148.html

Unfortunately, it cannot be reproduced doing only that; other factors that I cannot reproduce played a role too.

Version-Release number of selected component:
epiphany-runtime-3.16.3-2.fc22

Additional info:
reporter:       libreport-2.6.3
backtrace_rating: 4
cmdline:        epiphany
crash_function: g_type_check_instance_is_a
executable:     /usr/bin/epiphany
global_pid:     4089
kernel:         4.2.5-201.fc22.x86_64
runlevel:       N 5
type:           CCpp
uid:            1000

Truncated backtrace:
Thread no. 1 (10 frames)
 #0 g_type_check_instance_is_a at gtype.c:4016
 #1 webkit_web_view_get_favicon at /usr/src/debug/webkitgtk-2.8.5/Source/WebKit2/UIProcess/API/gtk/WebKitWebView.cpp:2666
 #2 save_snapshot at ephy-snapshot-service.c:196
 #3 on_snapshot_ready at ephy-snapshot-service.c:223
 #4 g_task_return_now at gtask.c:1088
 #5 g_task_return at gtask.c:1146
 #6 webKitWebViewDidReceiveSnapshot at /usr/src/debug/webkitgtk-2.8.5/Source/WebKit2/UIProcess/API/gtk/WebKitWebView.cpp:3443
 #7 didReceiveWebViewMessageFromInjectedBundle at /usr/src/debug/webkitgtk-2.8.5/Source/WebKit2/UIProcess/API/gtk/WebKitInjectedBundleClient.cpp:101
 #8 didReceiveMessageFromInjectedBundle at /usr/src/debug/webkitgtk-2.8.5/Source/WebKit2/UIProcess/API/gtk/WebKitInjectedBundleClient.cpp:120
 #9 WebKit::WebContextInjectedBundleClient::didReceiveMessageFromInjectedBundle at /usr/src/debug/webkitgtk-2.8.5/Source/WebKit2/UIProcess/WebContextInjectedBundleClient.cpp:42