pushFwd incorrect behavior on certain rings produced by flattenRing

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Hi all,
I haven't figured out why exactly this is happening, but it when I produce rings by flattening them, `pushFwd` from the `PushForward` package has errors / gives the wrong result.

```
i1 : needsPackage "PushForward"

o1 = PushForward

o1 : Package

i2 : k = QQ[x]/ideal(x^3-2)

o2 = k

o2 : QuotientRing

i3 : L = k[y]/ideal(y^2-2)

o3 = L

o3 : QuotientRing

i4 : S2 = (flattenRing(L))#0

o4 = S2

o4 : QuotientRing

i5 : (myMod, myGens, myFun) = pushFwd(map(S2, coefficientRing S2))

o5 = (cokernel | 0 0 0 0 |, | 1 y yx yx2 x x2 |, myFun)
| 0 0 0 0 |
| 1 0 0 0 |
| 0 1 0 0 |
| 0 0 1 0 |
| 0 0 0 1 |

o5 : Sequence

i6 : myFun(x)
stdio:6:5:(3): error: rawFreeModule: degree rank 0, but sequence of degrees given

i8 : prune myMod

2
o8 = QQ

o8 : QQ-module, free
```

In this case, the push forward should obviously be degree 6. However, if I set the MonomialOrder to GRevLex and the degrees to 1, it's ok, and it gives the correct answer.

```
i13 : S4 = newRing(S2, MonomialOrder=>GRevLex, Degrees=>{1,1})

o13 = S4

o13 : QuotientRing

i14 : (myMod, myGens, myFun) = pushFwd(map(S4, coefficientRing S4))

6
o14 = (QQ , | 1 y yx yx2 x x2 |, myFun)

o14 : Sequence

i15 : myFun(x)

o15 = | 0 |
| 0 |
| 0 |
| 0 |
| 1 |
| 0 |

6 1
o15 : Matrix QQ <-- QQ
```
For comparison:
```
i17 : S2#FlatMonoid

o17 = monoid[y, x, Degrees => {{1}, {0}}, Heft => {2:1}, MonomialOrder => {MonomialSize => 32}]
{0} {1} {GRevLex => {1} }
{Position => Up }
{GRevLex => {1} }

o17 : GeneralOrderedMonoid

i18 : S4#FlatMonoid

o18 = monoid[y, x, Degrees => {2:1}, Heft => {1}]

o18 : GeneralOrderedMonoid
```

Reproduce the transcript using the PushForward package, focusing on pushFwd applied to the ring produced by flattenRing and comparing S2 with the GRevLex S4 case. Inspect how the generated grading and monomial order are handled; done means pushFwd returns the expected degree-6 module and matrix for S2 without regressing the working case.

Written by the indexing model from the issue text.