Fix unknown classes and ERS API improvement (#264) #1841

All 2 469 tests pass, 44 skipped in 22m 19s

84 files ±0 84 suites ±0 22m 19s ⏱️ - 1m 13s
2 513 tests +1 2 469 ✅ +1 44 💤 ±0 0 ❌ ±0
2 541 runs +1 2 497 ✅ +1 44 💤 ±0 0 ❌ ±0

Results for commit 788d041. ± Comparison against earlier commit 549cc20.