Fix some missing default cases and possible fall-through issues.

src/main/java/com/gmail/nossr50/util/BlockChecks.java

@@ -162,10 +162,12 @@ public final class BlockChecks {
             return true;
         case SMOOTH_BRICK:
         case COBBLE_WALL:
-            if (block.getData() == 0) {
+            if (block.getData() == (byte)0x0) {
                 return true;
             }
 
+            return false;
+
         default:
             return false;
         }

src/main/java/com/gmail/nossr50/util/ItemChecks.java

@@ -564,6 +564,8 @@ public class ItemChecks {
                 return true;
             }
 
+            return false;
+
         default:
             return false;
         }