$ sudo apt-get -f install
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages will be REMOVED:
  linux-image-extra-3.13.0-43-generic
0 upgraded, 0 newly installed, 1 to remove and 0 not upgraded.
3 not fully installed or removed.
After this operation, 152 MB disk space will be freed.
Do you want to continue? [Y/n] 
(Reading database ... 194410 files and directories currently installed.)
Removing linux-image-extra-3.13.0-43-generic (3.13.0-43.72) ...
run-parts: executing /etc/kernel/postinst.d/apt-auto-removal 3.13.0-43-generic /boot/vmlinuz-3.13.0-43-generic
run-parts: executing /etc/kernel/postinst.d/dkms 3.13.0-43-generic /boot/vmlinuz-3.13.0-43-generic
run-parts: executing /etc/kernel/postinst.d/initramfs-tools 3.13.0-43-generic /boot/vmlinuz-3.13.0-43-generic
update-initramfs: Generating /boot/initrd.img-3.13.0-43-generic
W: mdadm: the array /dev/md/monolith:0 with UUID 826ef9b8:1c282186:82586683:e0b960b3
W: mdadm: is currently active, but it is not listed in mdadm.conf. if
W: mdadm: it is needed for boot, then YOUR SYSTEM IS NOW UNBOOTABLE!
W: mdadm: please inspect the output of /usr/share/mdadm/mkconf, compare
W: mdadm: it to /etc/mdadm/mdadm.conf, and make the necessary changes.
run-parts: executing /etc/kernel/postinst.d/pm-utils 3.13.0-43-generic /boot/vmlinuz-3.13.0-43-generic
run-parts: executing /etc/kernel/postinst.d/update-notifier 3.13.0-43-generic /boot/vmlinuz-3.13.0-43-generic
run-parts: executing /etc/kernel/postinst.d/zz-update-grub 3.13.0-43-generic /boot/vmlinuz-3.13.0-43-generic
/usr/sbin/grub-mkconfig: 48: /etc/default/grub: function: not found
run-parts: /etc/kernel/postinst.d/zz-update-grub exited with return code 127
dpkg: error processing package linux-image-extra-3.13.0-43-generic (--remove):
 subprocess installed post-removal script returned error exit status 1
Errors were encountered while processing:
 linux-image-extra-3.13.0-43-generic
E: Sub-process /usr/bin/dpkg returned an error code (1)