OPT-36: test_opt36 reads possibly-missing values through nth()

Co-Authored-By: Claude <noreply@anthropic.com>

goodwe_controller/test_opt36.py

@@ -40,6 +40,7 @@ sys.path.insert(0, HERE)
 sys.path.insert(0, os.path.join(HERE, "tools"))
 logging.disable(logging.WARNING)
 
+from named_absence import nth                                   # noqa: E402
 import ux54_scenarios as S                                      # noqa: E402
 import opt11p3_replay as rp                                     # noqa: E402
 import app.main as m                                            # noqa: E402
@@ -157,10 +158,10 @@ for lang in ("en", "nl"):
           f"({[r['kind'] for r in mine]})",
           [r["kind"] for r in mine] == ["give"])
     check(f"{lang}: A's give block is what A holds (60 % -> 6.1 kWh)",
-          abs(mine[0]["kwh"] - (60.0 - FLOOR) / 100.0 * CAP_A) < 0.01)
+          abs(nth(mine, 0)["kwh"] - (60.0 - FLOOR) / 100.0 * CAP_A) < 0.01)
     check(f"{lang}: B's give block reads B after its charge (to 95 %: "
           "15.4 kWh, not 15.2 from 94 %)",
-          abs(theirs[-1]["kwh"] - (CEIL - FLOOR) / 100.0 * CAP_B) < 0.01)
+          abs(nth(theirs, -1)["kwh"] - (CEIL - FLOOR) / 100.0 * CAP_B) < 0.01)
     check(f"{lang}: the solar line has no 'the rest' sentence",
           "0.4" not in line and "0,4" not in line
           and "rest, " not in line and "rest van" not in line