for trivial cocycle return 1

Modularity.m

@@ -388,6 +388,10 @@ intrinsic ModPrimes(m :: Modularity, R2 :: FldNum,
   discR1 := Discriminant(m`R1);
   //tl := show_classes(proj, phi);
   fc := frobenius_classes(proj : no_order:=no_order, only_order:=only_order);
+  if &and [tr(phi(x)) eq 0 : x in fc[a], a in Keys(fc)] then
+    // a cocycle with all traces equal to 0 is ok
+    return 1;
+  end if;
   //print [<a,tl[a]> : a in Keys(tl)];
   /*
   if &and [tl[a,1] ne 0 : a in Keys(tl)] then