Fix improper treatment of unbreakable blocks

src/main/java/baritone/utils/ToolSet.java

@@ -77,7 +77,7 @@ public class ToolSet implements Helper {
 
     /**
      * Calculates how long would it take to mine the specified block given the best tool
-     * in this toolset is used.
+     * in this toolset is used. A negative value is returned if the specified block is unbreakable.
      *
      * @param state the blockstate to be mined
      * @return how long it would take in ticks
@@ -87,9 +87,8 @@ public class ToolSet implements Helper {
         ItemStack contents = player().inventory.getStackInSlot(slot);
 
         float blockHard = state.getBlockHardness(null, null);
-        if (blockHard < 0) {
-            return 0;
-        }
+        if (blockHard < 0)
+            return -1;
 
         float speed = contents.getDestroySpeed(state);
         if (speed > 1) {