feature: Add $feature_flag_error property to track flag evaluation failures
#1243
| Job | Run time |
|---|---|
| 23s | |
| 25s | |
| 2m 38s | |
| 2m 23s | |
| 2m 19s | |
| 2m 28s | |
| 2m 38s | |
| 13m 14s |