Add better SDESystem error when it hasn't been structural_simplify
#5955
| Job | Run time |
|---|---|
| 46m 24s | |
| 34s | |
| 16m 54s | |
| 48m 8s | |
| 24m 9s | |
| 15m 6s | |
| 26m 17s | |
| 30m 29s | |
| 32s | |
| 19m 18s | |
| 25m 47s | |
| 20m 21s | |
| 16m 55s | |
| 4h 50m 54s |