[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 classinfo2;

class C
{
}

class D : C
{
}

void main()
{
    D d;
    d = new D;
    ClassInfo ci = d.classinfo;
    assert(ci is D.classinfo);
}