Actually, it does die, but only in the debugger.

% perl -d -e '$#{@1}'
Default die handler restored.

Loading DB routines from perl5db.pl version 1.07
Editor support available.

Enter h or `h h' for help, or `man perldebug' for more help.

main::(-e:1):    $#{@1}
  DB<1> c
Bizarre copy of ARRAY in leave at -e line 1.
Debugged program terminated.
[download]

Without the debugger, it works fine.

This error message is created in sv.c, in the function Perl_sv_setsv. This function copies a scalar value from one location to another. "Bizarre copy of ARRAY in leave" means that an opcode called "leave" tried to copy an array to a scalar, should be impossible. "leave" is the opcode for leaving a block of code. Why this happened, I cannot figure out.