fix that null exception

src/api/java/baritone/api/process/PathingCommandType.java

@@ -51,5 +51,10 @@ public enum PathingCommandType {
      * <p>
      * Cancel the current path if the goals are not equal
      */
-    FORCE_REVALIDATE_GOAL_AND_PATH
+    FORCE_REVALIDATE_GOAL_AND_PATH,
+
+    /**
+     * Go and ask the next process what to do
+     */
+    DEFER
 }

src/main/java/baritone/process/BackfillProcess.java

@@ -87,7 +87,7 @@ public class BackfillProcess extends BaritoneProcessHelper {
                     return new PathingCommand(null, PathingCommandType.REQUEST_PAUSE);
             }
         }
-        return null; // cede to other process
+        return new PathingCommand(null, PathingCommandType.DEFER); // cede to other process
     }
 
     public void amIBreakingABlockHMMMMMMM() {
@@ -119,7 +119,7 @@ public class BackfillProcess extends BaritoneProcessHelper {
 
     @Override
     public void onLostControl() {
-        blocksToReplace = new HashMap<>();
+        blocksToReplace.clear();
     }
 
     @Override

src/main/java/baritone/utils/PathingControlManager.java

@@ -199,11 +199,11 @@ public class PathingControlManager implements IPathingControlManager {
 
             PathingCommand exec = proc.onTick(Objects.equals(proc, inControlLastTick) && baritone.getPathingBehavior().calcFailedLastTick(), baritone.getPathingBehavior().isSafeToCancel());
             if (exec == null) {
-                /*if (proc.isActive()) {
-                    throw new IllegalStateException(proc.displayName() + " returned null PathingCommand");
+                if (proc.isActive()) {
+                    throw new IllegalStateException(proc.displayName() + " actively returned null PathingCommand");
                 }
-                proc.onLostControl();*/
-            } else {
+                // no need to call onLostControl; they are reporting inactive.
+            } else if (exec.commandType != PathingCommandType.DEFER) {
                 inControlThisTick = proc;
                 if (!proc.isTemporary()) {
                     iterator.forEachRemaining(IBaritoneProcess::onLostControl);