Perform SpringPP airport checks before calling AfterLoadVehicles.

This is because AfterLoadVehicles may indirectly check airport
properties via the NewGRF code.

Defer missing GRF error message output until the end of AfterLoadGame
to avoid obscuring any earlier errors.

src/saveload/afterload.cpp

@@ -698,12 +698,6 @@ bool AfterLoadGame()
 		return false;
 	}
 
-	switch (gcf_res) {
-		case GLC_COMPATIBLE: ShowErrorMessage(STR_NEWGRF_COMPATIBLE_LOAD_WARNING, INVALID_STRING_ID, WL_CRITICAL); break;
-		case GLC_NOT_FOUND:  ShowErrorMessage(STR_NEWGRF_DISABLED_WARNING, INVALID_STRING_ID, WL_CRITICAL); _pause_mode = PM_PAUSED_ERROR; break;
-		default: break;
-	}
-
 	/* The value of _date_fract got divided, so make sure that old games are converted correctly. */
 	if (IsSavegameVersionBefore(11, 1) || (IsSavegameVersionBefore(147) && _date_fract > DAY_TICKS)) _date_fract /= 885;
 
@@ -793,6 +787,55 @@ bool AfterLoadGame()
 		}
 	}
 
+
+	if (SlXvIsFeaturePresent(XSLFI_SPRINGPP)) {
+		/*
+		 * Reject huge airports
+		 * Annoyingly SpringPP v2.0.102 has a bug where it uses the same ID for AT_INTERCONTINENTAL2 and AT_OILRIG.
+		 * Do this here as AfterLoadVehicles might also check it indirectly via the newgrf code.
+		 */
+		Station *st;
+		FOR_ALL_STATIONS(st) {
+			if (st->airport.tile == INVALID_TILE) continue;
+			StringID err = INVALID_STRING_ID;
+			if (st->airport.type == 9) {
+				if (st->dock_tile != INVALID_TILE && IsOilRig(st->dock_tile)) {
+					/* this airport is probably an oil rig, not a huge airport */
+				} else {
+					err = STR_GAME_SAVELOAD_ERROR_HUGE_AIRPORTS_PRESENT;
+				}
+				st->airport.type = AT_OILRIG;
+			} else if (st->airport.type == 10) {
+				err = STR_GAME_SAVELOAD_ERROR_HUGE_AIRPORTS_PRESENT;
+			}
+			if (err != INVALID_STRING_ID) {
+				SetSaveLoadError(err);
+				/* Restore the signals */
+				ResetSignalHandlers();
+				return false;
+			}
+		}
+	}
+
+	if (SlXvIsFeaturePresent(XSLFI_SPRINGPP, 1, 1)) {
+		/*
+		 * Reject helicopters aproaching oil rigs using the wrong aircraft movement data
+		 * Annoyingly SpringPP v2.0.102 has a bug where it uses the same ID for AT_INTERCONTINENTAL2 and AT_OILRIG
+		 * Do this here as AfterLoadVehicles can also check it indirectly via the newgrf code.
+		 */
+		Aircraft *v;
+		FOR_ALL_AIRCRAFT(v) {
+			Station *st = GetTargetAirportIfValid(v);
+			if (st != NULL && ((st->dock_tile != INVALID_TILE && IsOilRig(st->dock_tile)) || st->airport.type == AT_OILRIG)) {
+				/* aircraft is on approach to an oil rig, bail out now */
+				SetSaveLoadError(STR_GAME_SAVELOAD_ERROR_HELI_OILRIG_BUG);
+				/* Restore the signals */
+				ResetSignalHandlers();
+				return false;
+			}
+		}
+	}
+
 	/* Update all vehicles */
 	AfterLoadVehicles(true);
 
@@ -3085,51 +3128,6 @@ bool AfterLoadGame()
 		DEBUG(sl, 3, "New inflation prices: %f", _economy.inflation_prices / 65536.0);
 	}
 
-	if (SlXvIsFeaturePresent(XSLFI_SPRINGPP)) {
-		/*
-		 * Reject huge airports
-		 * Annoyingly SpringPP v2.0.102 has a bug where it uses the same ID for AT_INTERCONTINENTAL2 and AT_OILRIG,
-		 */
-		Station *st;
-		FOR_ALL_STATIONS(st) {
-			if (st->airport.tile == INVALID_TILE) continue;
-			StringID err = INVALID_STRING_ID;
-			if (st->airport.type == 9) {
-				if (st->dock_tile != INVALID_TILE && IsOilRig(st->dock_tile)) {
-					/* this airport is probably an oil rig, not a huge airport */
-				} else {
-					err = STR_GAME_SAVELOAD_ERROR_HUGE_AIRPORTS_PRESENT;
-				}
-				st->airport.type = AT_OILRIG;
-			} else if (st->airport.type == 10) {
-				err = STR_GAME_SAVELOAD_ERROR_HUGE_AIRPORTS_PRESENT;
-			}
-			if (err != INVALID_STRING_ID) {
-				SetSaveLoadError(err);
-				/* Restore the signals */
-				ResetSignalHandlers();
-				return false;
-			}
-		}
-	}
-	if (SlXvIsFeaturePresent(XSLFI_SPRINGPP, 1, 1)) {
-		/*
-		 * Reject helicopters aproaching oil rigs using the wrong aircraft movement data
-		 * Annoyingly SpringPP v2.0.102 has a bug where it uses the same ID for AT_INTERCONTINENTAL2 and AT_OILRIG
-		 */
-		Aircraft *v;
-		FOR_ALL_AIRCRAFT(v) {
-			Station *st = GetTargetAirportIfValid(v);
-			if (st != NULL && st->dock_tile != INVALID_TILE && IsOilRig(st->dock_tile)) {
-				/* aircraft is on approach to an oil rig, bail out now */
-				SetSaveLoadError(STR_GAME_SAVELOAD_ERROR_HELI_OILRIG_BUG);
-				/* Restore the signals */
-				ResetSignalHandlers();
-				return false;
-			}
-		}
-	}
-
 	if (SlXvIsFeaturePresent(XSLFI_MIGHT_USE_PAX_SIGNALS) || SlXvIsFeatureMissing(XSLFI_TRACE_RESTRICT)) {
 		for (TileIndex t = 0; t < map_size; t++) {
 			if (HasStationTileRail(t)) {
@@ -3199,6 +3197,14 @@ bool AfterLoadGame()
 	AfterLoadLinkGraphs();
 
 	AfterLoadTraceRestrict();
+
+	/* Show this message last to avoid covering up an error message if we bail out part way */
+	switch (gcf_res) {
+		case GLC_COMPATIBLE: ShowErrorMessage(STR_NEWGRF_COMPATIBLE_LOAD_WARNING, INVALID_STRING_ID, WL_CRITICAL); break;
+		case GLC_NOT_FOUND:  ShowErrorMessage(STR_NEWGRF_DISABLED_WARNING, INVALID_STRING_ID, WL_CRITICAL); _pause_mode = PM_PAUSED_ERROR; break;
+		default: break;
+	}
+
 	return true;
 }