Crashes on self-upgrade nix 2.6.1

[hedefalk]

Describe the bug

To Reproduce Steps to reproduce the behavior:

1. ✗ lorri self-upgrade

Expected behavior

upgraded:

Result

Building ...
lorri had a problem and crashed. To help us diagnose the problem you can send us a crash report.

We have generated a report file at "/var/folders/s_/qdwr96yj3zv0vy21sdzzlx3m0000gn/T/report-0b0f3707-25a4-4126-9a71-1a1ecda0b1b2.toml". Submit an issue or email with the subject of "lorri Crash Report" and include the report as an attachment.

Metadata

name = 'lorri'
operating_system = 'unix:OSX'
crate_version = '1.5.0'
explanation = '''
Panic occurred in file 'src/ops.rs' at line 820
'''
cause = '''
Failed to build the update! Exit {
    cmd: "\"nix-build\" \"--out-link\" \"/var/folders/s_/qdwr96yj3zv0vy21sdzzlx3m0000gn/T/.tmp550VQH/result\" \"-A\" \"package\" \"--argstr\" \"type\" \"branch\" \"--argstr\" \"branch\" \"rolling-release\" \"--\" \"/Users/viktor/Library/Caches/com.github.nix-community.lorri.lorri.lorri/cas/a9146ec9593a3cbfad08b432f09c4a9e\"",
    status: Some(
        1,
    ),
    logs: [
        LogLine(
            "error: cannot coerce null to a string",
        ),
        LogLine(
            "",
        ),
        LogLine(
            "       at /nix/store/mbhz2ijd6103h2k6vxcr6xk4dqln4iwk-source/pkgs/build-support/cc-wrapper/default.nix:151:12:",
        ),
        LogLine(
            "",
        ),
        LogLine(
            "          150|     + (if nativeTools then \'\'",
        ),
        LogLine(
            "          151|       echo ${if targetPlatform.isDarwin then cc else nativePrefix} > $out/nix-support/orig-cc",
        ),
        LogLine(
            "             |            ^",
        ),
        LogLine(
            "          152|",
        ),
        LogLine(
            "(use \'--show-trace\' to show detailed location information)",
        ),
    ],
}'''
method = 'Panic'
backtrace = '''

   0: 0x104592a84 - rust_begin_unwind
   1: 0x1045c672c - core::panicking::panic_fmt::h86b1a7d6919789bf
   2: 0x10441a19c - lorri::ops::upgrade::h37e9d01f3191d671
   3: 0x1043d8e08 - lorri::main::hf2dfc92ff7c48473
   4: 0x1043daf30 - std::sys_common::backtrace::__rust_begin_short_backtrace::hbf6e341df8a7fe95
   5: 0x1043dd1b4 - std::rt::lang_start::{{closure}}::h078f3270237d0daf
   6: 0x104587080 - std::rt::lang_start_internal::h84ad1a7bd4a04865
   7: 0x1043da0c8 - main'''