LLDB: warning: initialization of variable '$__lldb_error_result'

import Foundation

final class Foo {
    func bar() {
        DispatchQueue.main.async { [weak self] in
            if let `self` = self {
                print(self)
            }
        }
    }
}

let foo = Foo()
foo.bar()
dispatchMain()

error: warning: <EXPR>:12:9: warning: initialization of variable '$__lldb_error_result' was never used; consider replacing with assignment to '_' or removing it
    var $__lldb_error_result = __lldb_tmp_error
    ~~~~^~~~~~~~~~~~~~~~~~~~
    _

error: <EXPR>:18:5: error: value of type 'Foo' has no member '$__lldb_wrapped_expr_0'
    $__lldb_injected_self.$__lldb_wrapped_expr_0(
    ^~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~

$ swiftc -g foo.swift
$ lldb ./foo
(lldb) target create "./foo"
Current executable set to './foo' (x86_64).
(lldb) br set -f foo.swift -l 7
Breakpoint 1: where = foo`closure #1 () -> () in foo.Foo.bar() -> () + 118 at foo.swift:7, address = 0x0000000100001ec6
(lldb) r
...
Target 0: (foo) stopped.
(lldb) po self
error: warning: <EXPR>:12:9: warning: initialization of variable '$__lldb_error_result' was never used; consider replacing with assignment to '_' or removing it
    var $__lldb_error_result = __lldb_tmp_error
    ~~~~^~~~~~~~~~~~~~~~~~~~
    _

error: <EXPR>:18:5: error: value of type 'Foo' has no member '$__lldb_wrapped_expr_0'
    $__lldb_injected_self.$__lldb_wrapped_expr_0(
    ^~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~~~~~