Search mask ^W and non-ASCII characters

[nmeum]

I am using the following ncmpc version:

$ ncmpc --version
ncmpc version: 0.29
build options: debug multibyte wide locale nls colors getmouse artist-screen help-screen search-screen song-screen key-screen lyrics-screen outputs-screen

configuration files:
 /home/nmeum/.ncmpc/config
 /etc/ncmpc/config

When entering a search string in the Search: input bar (which can be reached by pressing 5 twice) which contains non-ASCII character (e.g the german umlaut 'ö'), pressing Ctrl + W triggers an assertion and causes the program to crash.

Here is the output of the assert(3) call:

Search: fööAssertion failed: x < strlen(wr->line) (../src/wreadln.c: wreadln_delete_char: 355)
 Aborted

I can reproduce this crash on both Alpine Linux Edge and Arch Linux.