add cost verification lookahead

src/main/java/baritone/Settings.java

@@ -119,6 +119,13 @@ public class Settings {
      */
     public Setting<Boolean> cutoffAtLoadBoundary = new Setting<>(true);
 
+    /**
+     * Stop 5 movements before anything that made the path COST_INF.
+     * For example, if lava has spread across the path, don't walk right up to it then recalculate, it might
+     * still be spreading lol
+     */
+    public Setting<Integer> costVerificationLookahead = new Setting<>(5);
+
     /**
      * Static cutoff factor. 0.9 means cut off the last 10% of all paths, regardless of chunk load state
      */

src/main/java/baritone/pathing/path/PathExecutor.java

@@ -211,6 +211,15 @@ public class PathExecutor implements Helper {
             Baritone.INSTANCE.getInputOverrideHandler().clearAllKeys();
             return true;
         }
+        for (int i = 1; i < Baritone.settings().costVerificationLookahead.get() && pathPosition + i < path.length() - 1; i++) {
+            if (path.movements().get(pathPosition + 1).recalculateCost() >= ActionCosts.COST_INF) {
+                displayChatMessageRaw("Something has changed in the world and a future movement has become impossible. Cancelling.");
+                pathPosition = path.length() + 3;
+                failed = true;
+                Baritone.INSTANCE.getInputOverrideHandler().clearAllKeys();
+                return true;
+            }
+        }
         if (costEstimateIndex == null || costEstimateIndex != pathPosition) {
             costEstimateIndex = pathPosition;
             currentMovementInitialCostEstimate = currentCost; // do this only once, when the movement starts