[svn r378] Make some errors fatal to prevent segfaults. Error instead of assert on missing label. Fixes: nocompile/ finally_02, 03, 07, 08 goto_16_A, 16_B, 12, 13, 14

module bug4;

int func(int i)
{
    i += 2;
    i -= 3;
    return i;
}

void main()
{
    assert(func(4) == 3);
}