I did something similar in Devel::TraceMethods (hey, I invented a wheel!). The only approach that worked for me was to copy all the other typeglob slots to a temporary array, undefine the destination typeglob altogether, then assign a subroutine reference and the other references. In this case, $src is a reference to the symbol table containing the subroutine to wrap, and $symbol is the name of the subroutine in that table:

# save all other slots of the typeglob
foreach my $slot (qw( SCALAR ARRAY HASH IO FORMAT )) {
    my $elem = *{ $src->{$symbol} }{$slot};
        next unless defined $elem;
        push @slots, $elem;
    }

    # clear out the source glob
    #       undef &{ *{$src->{$symbol}} } didn't work
    undef $src->{$symbol};

    # replace the sub in the source
    $src->{$symbol} = sub {
        logCall->($symbol, @_);
        return $sub->(@_);
    };

    # replace the other slot elements
    foreach my $elem (@slots) {
        $src->{$symbol} = $elem;
    }
}
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