Package doesn't install cleanly, then won't uninstall cleanly

[Erik de Castro Lopo]

On Karmic i386.

$ apt-get install flashplugin-installer

    Preconfiguring packages ...
    Selecting previously deselected package flashplugin-installer.
    (Reading database ... 344296 files and directories currently installed.)
    Preparing to replace flashplugin-installer 10.0.22.87ubuntu2 (using .../flashplugin-installer_10.0.22.87ubuntu2_i386.deb) ...
    update-alternatives: error: no alternatives for iceape-flashplugin.
    update-alternatives: error: no alternatives for iceape-flashplugin.
    dpkg: warning: old pre-removal script returned error exit status 2
    dpkg - trying script from the new package instead ...
    prerm called with unknown argument `failed-upgrade'
    dpkg: error processing /var/cache/apt/archives/flashplugin-installer_10.0.22.87ubuntu2_i386.deb (--unpack):
 subprocess new pre-removal script returned error exit status 1
    postinst called with argument `abort-upgrade'
    dpkg: error while cleaning up:
      subprocess installed post-installation script returned error exit status 1
    Errors were encountered while processing:
      /var/cache/apt/archives/flashplugin-installer_10.0.22.87ubuntu2_i386.deb
    E: Sub-process /usr/bin/dpkg returned an error code (1)

$ apt-get remove flashplugin-installer

    The following packages will be REMOVED:
      flashplugin-installer
    0 upgraded, 0 newly installed, 1 to remove and 0 not upgraded.
    After this operation, 180kB disk space will be freed.
    Do you want to continue [Y/n]?
    dpkg: error processing flashplugin-installer (--remove):
     Package is in a very bad inconsistent state - you should
     reinstall it before attempting a removal.
    Errors were encountered while processing:
     flashplugin-installer
    E: Sub-process /usr/bin/dpkg returned an error code (1)

$ dpkg --purge --force-all flashplugin-installer

    dpkg: warning: overriding problem because --force enabled:
     Package is in a very bad inconsistent state - you should
     reinstall it before attempting a removal.
    (Reading database ... 344294 files and directories currently installed.)
    Removing flashplugin-installer ...
    update-alternatives: error: no alternatives for iceape-flashplugin.
    update-alternatives: error: no alternatives for iceape-flashplugin.
    dpkg: error processing flashplugin-installer (--purge):
     subprocess installed pre-removal script returned error exit status 2
    postinst called with argument `abort-remove'
    dpkg: error while cleaning up:
     subprocess installed post-installation script returned error exit status 1
    Errors were encountered while processing:
      flashplugin-installer