flamegraph --completions zsh crashes #158

$ RUST_BACKTRACE=full flamegraph --completions zsh
thread 'main' panicked at 'Fatal internal error. Please consider filing a bug report at https://github.com/clap-rs/clap/issues', /Users/kamyar/.cargo/registry/src/github.life-white.uk-1ecc6299db9ec823/clap-2.33.3/src/completions/zsh.rs:346:29
stack backtrace:
   0:        0x1022269e4 - std::backtrace_rs::backtrace::libunwind::trace::h5bc01f52da331a76
                               at /rustc/c8dfcfe046a7680554bf4eb612bad840e7631c4b/library/std/src/../../backtrace/src/backtrace/libunwind.rs:90:5
   1:        0x1022269e4 - std::backtrace_rs::backtrace::trace_unsynchronized::hed9f5f7d35868621
                               at /rustc/c8dfcfe046a7680554bf4eb612bad840e7631c4b/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:        0x1022269e4 - std::sys_common::backtrace::_print_fmt::hbabfbab394a5b2a4
                               at /rustc/c8dfcfe046a7680554bf4eb612bad840e7631c4b/library/std/src/sys_common/backtrace.rs:67:5
   3:        0x1022269e4 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::he94cf96d727dca88
                               at /rustc/c8dfcfe046a7680554bf4eb612bad840e7631c4b/library/std/src/sys_common/backtrace.rs:46:22
   4:        0x102243ccc - core::fmt::write::hba755d202326a972
                               at /rustc/c8dfcfe046a7680554bf4eb612bad840e7631c4b/library/core/src/fmt/mod.rs:1115:17
   5:        0x1022242f8 - std::io::Write::write_fmt::h2e794551090dcd0d
                               at /rustc/c8dfcfe046a7680554bf4eb612bad840e7631c4b/library/std/src/io/mod.rs:1665:15
   6:        0x10222862c - std::sys_common::backtrace::_print::hb13f9bf532a85f20
                               at /rustc/c8dfcfe046a7680554bf4eb612bad840e7631c4b/library/std/src/sys_common/backtrace.rs:49:5
   7:        0x10222862c - std::sys_common::backtrace::print::h8bcbb8e054752f0b
                               at /rustc/c8dfcfe046a7680554bf4eb612bad840e7631c4b/library/std/src/sys_common/backtrace.rs:36:9
   8:        0x10222862c - std::panicking::default_hook::{{closure}}::ha49ee092c99defdc
                               at /rustc/c8dfcfe046a7680554bf4eb612bad840e7631c4b/library/std/src/panicking.rs:208:50
   9:        0x102228160 - std::panicking::default_hook::h878922f48a642f60
                               at /rustc/c8dfcfe046a7680554bf4eb612bad840e7631c4b/library/std/src/panicking.rs:225:9
  10:        0x102228c74 - std::panicking::rust_panic_with_hook::h1daadfa06b290a08
                               at /rustc/c8dfcfe046a7680554bf4eb612bad840e7631c4b/library/std/src/panicking.rs:622:17
  11:        0x1022287bc - std::panicking::begin_panic_handler::{{closure}}::h34f1299f5ae837e5
                               at /rustc/c8dfcfe046a7680554bf4eb612bad840e7631c4b/library/std/src/panicking.rs:519:13
  12:        0x102226e74 - std::sys_common::backtrace::__rust_end_short_backtrace::hcec1a6222a82e10c
                               at /rustc/c8dfcfe046a7680554bf4eb612bad840e7631c4b/library/std/src/sys_common/backtrace.rs:141:18
  13:        0x102228720 - rust_begin_unwind
                               at /rustc/c8dfcfe046a7680554bf4eb612bad840e7631c4b/library/std/src/panicking.rs:515:5
  14:        0x1022503b8 - core::panicking::panic_fmt::hb50b2a93e2b2795f
                               at /rustc/c8dfcfe046a7680554bf4eb612bad840e7631c4b/library/core/src/panicking.rs:92:14
  15:        0x102250304 - core::option::expect_failed::h98d7c7a72053f7b6
                               at /rustc/c8dfcfe046a7680554bf4eb612bad840e7631c4b/library/core/src/option.rs:1578:5
  16:        0x10220afb0 - clap::completions::zsh::get_args_of::h070f747b50c18ba1
  17:        0x10217b670 - clap::completions::zsh::ZshGen::generate_to::he4e74f92a6e9dc06
  18:        0x10217b97c - clap::completions::ComplGen::generate::h369edff8ec4f9b6c
  19:        0x10217bb0c - clap::app::App::gen_completions_to::h38f128a32464be2b
  20:        0x10217ed44 - flamegraph::main::h9b2e9775ebb960db
  21:        0x10217f764 - std::sys_common::backtrace::__rust_begin_short_backtrace::hcd4cecc7fa8f43f2
  22:        0x10217b400 - std::rt::lang_start::{{closure}}::ha60831df255221cc
  23:        0x10222914c - core::ops::function::impls::<impl core::ops::function::FnOnce<A> for &F>::call_once::he38288968a08ce30
                               at /rustc/c8dfcfe046a7680554bf4eb612bad840e7631c4b/library/core/src/ops/function.rs:259:13
  24:        0x10222914c - std::panicking::try::do_call::hc5ee1d2a64b67a7c
                               at /rustc/c8dfcfe046a7680554bf4eb612bad840e7631c4b/library/std/src/panicking.rs:401:40
  25:        0x10222914c - std::panicking::try::h6456708f12a6b661
                               at /rustc/c8dfcfe046a7680554bf4eb612bad840e7631c4b/library/std/src/panicking.rs:365:19
  26:        0x10222914c - std::panic::catch_unwind::h0912a030777d678b
                               at /rustc/c8dfcfe046a7680554bf4eb612bad840e7631c4b/library/std/src/panic.rs:434:14
  27:        0x10222914c - std::rt::lang_start_internal::{{closure}}::hd9cb206594099c49
                               at /rustc/c8dfcfe046a7680554bf4eb612bad840e7631c4b/library/std/src/rt.rs:45:48
  28:        0x10222914c - std::panicking::try::do_call::h75969ed557adb08d
                               at /rustc/c8dfcfe046a7680554bf4eb612bad840e7631c4b/library/std/src/panicking.rs:401:40
  29:        0x10222914c - std::panicking::try::hd457662d949840e3
                               at /rustc/c8dfcfe046a7680554bf4eb612bad840e7631c4b/library/std/src/panicking.rs:365:19
  30:        0x10222914c - std::panic::catch_unwind::he3438363c58e9600
                               at /rustc/c8dfcfe046a7680554bf4eb612bad840e7631c4b/library/std/src/panic.rs:434:14
  31:        0x10222914c - std::rt::lang_start_internal::h103433e957e14c30
                               at /rustc/c8dfcfe046a7680554bf4eb612bad840e7631c4b/library/std/src/rt.rs:45:20
  32:        0x10217f394 - _main