Stack trace of thread 3088:
#0 0x00007f0eedee95f8 raise (libc.so.6)
#1 0x00007f0eedeeaa7a abort (libc.so.6)
#2 0x00007f0eedf2805a __libc_message (libc.so.6)
#3 0x00007f0eedf2d9a6 malloc_printerr (libc.so.6)
#4 0x00007f0eedf2e18e _int_free (libc.so.6)
#5 0x0000000000417836 n/a (htop)
#6 0x0000000000418e24 n/a (htop)
#7 0x0000000000417b1e n/a (htop)
#8 0x000000000041984c ProcessList_goThroughEntries (htop)
#9 0x000000000040f700 ProcessList_scan (htop)
#10 0x00000000004075da main (htop)
#11 0x00007f0eeded6610 __libc_start_main (libc.so.6)
#12 0x0000000000407749 _start (htop)

.config/htop/htoprc:
# Beware! This file is rewritten by htop when settings are changed in the interface.
# The parser is also very primitive, and not human-friendly.
fields=0 48 17 18 38 39 40 2 46 47 49 1
sort_key=46
sort_direction=1
hide_threads=0
hide_kernel_threads=0
hide_userland_threads=1
shadow_other_users=0
show_thread_names=1
highlight_base_name=1
highlight_megabytes=1
highlight_threads=1
tree_view=1
header_margin=0
detailed_cpu_time=1
cpu_count_from_zero=0
update_process_names=1
account_guest_in_cpu_meter=1
color_scheme=0
delay=15
left_meters=Memory AllCPUs2
left_meter_modes=1 1
right_meters=Tasks LoadAverage Uptime
right_meter_modes=2 2 2

After removing/renaming the old config, htop starts and runs normally.
I suggest a .install notice.