Add better SDESystem error when it hasn't been structural_simplify
#5911
| Job | Run time |
|---|---|
| 46m 42s | |
| 37s | |
| 17m 17s | |
| 24m 35s | |
| 24m 13s | |
| 15m 39s | |
| 27m 10s | |
| 30m 22s | |
| 34s | |
| 19m 46s | |
| 27m 37s | |
| 20m 47s | |
| 16m 13s | |
| 4h 31m 32s |