The bug

The death message for being shot by a Wither Skull is grammatically incorrect for certain entities. For example, if the player is shot by a Wither Skull from a Wither with a name that begins with a vowel, the death message below would not quite fit well:

<player> was shot by a Ender Storm's skull

The bug relates to MC-188392.

Fix

The death message should be replaced with the following below to fit for all entities:

<player> was shot by a wither skull from <entity>

A resource pack is provided below for the fix above.