Avoid `IndexDefect` when Prague EL sends malformed requests (#6822) #18333

All 4 980 tests pass, 347 skipped in 1h 3m 14s

      12 files ±0   1 822 suites ±0 1h 3m 14s ⏱️ + 3m 44s
  5 327 tests ±0   4 980 ✔️ ±0 347 💤 ±0 0 ❌ ±0
29 521 runs ±0 29 077 ✔️ ±0 444 💤 ±0 0 ❌ ±0

Results for commit a0f5e99. ± Comparison against earlier commit d1bdc13.