Description of problem:
I was copying a selection of files to a folder, and while that was processing, I selected "Send" on an open email I was composing.  That was when the crash occurred.

Version-Release number of selected component:
evolution-3.28.2-1.fc28

Additional info:
reporter:       libreport-2.9.5
backtrace_rating: 4
cmdline:        /usr/bin/evolution
crash_function: e_attachment_store_get_num_attachments
executable:     /usr/bin/evolution
journald_cursor: s=4b81908c6f07434585d34d16b8d62aec;i=2822;b=d8165f8284424eb8988fdd7e8f335c6e;m=2b15fc9d2;t=56d3a90662ae1;x=7a38fc5d2c6827e4
kernel:         4.16.11-300.fc28.x86_64
rootdir:        /
runlevel:       N 5
type:           CCpp
uid:            111765

Truncated backtrace:
Thread no. 1 (7 frames)
 #0 e_attachment_store_get_num_attachments at /usr/src/debug/evolution-3.28.2-1.fc28.x86_64/src/e-util/e-attachment-store.c:542
 #1 composer_build_message at /usr/src/debug/evolution-3.28.2-1.fc28.x86_64/src/composer/e-msg-composer.c:1479
 #2 e_msg_composer_get_message_draft at /usr/src/debug/evolution-3.28.2-1.fc28.x86_64/src/composer/e-msg-composer.c:5179
 #3 save_snapshot_replace_cb at /usr/src/debug/evolution-3.28.2-1.fc28.x86_64/src/modules/composer-autosave/e-autosave-utils.c:329
 #4 g_task_return_now at gtask.c:1148
 #5 complete_in_idle_cb at gtask.c:1162
 #11 gtk_main at gtkmain.c:1323

Potential duplicate: bug 1554146