feature: Add $feature_flag_error property to track flag evaluation failures
#1237
| Job | Run time |
|---|---|
| 19s | |
| 2m 15s | |
| 2m 10s | |
| 2m 25s | |
| 2m 23s | |
| 24s | |
| 2m 23s | |
| 12m 19s |