working on leveldb issues

was broken in minetestmapper-numpy

minetestmapper-expertmm.py

@@ -375,7 +375,7 @@ if os.path.exists(path + "sectors"):
         zlist.append(z)
 
 if len(xlist) == 0 or len(zlist) == 0:
-    print("At this location, data does not exist.")
+    print("At this location data does not exist.")
     sys.exit(1)
 
 # Get rid of doubles

minetestmapper-numpy.py

@@ -464,8 +464,11 @@ class LVLDB:
 
     def __iter__(self):
         for k in self.conn.RangeIter():
+            if k is not None and len(k)>0:
                 x, y, z = getIntegerAsBlock(int(k[0]))
                 yield x, y, z, k[0]
+            else:
+                print("WARNING: no data at first index in value '"+str(k))
 
     def get(self, pos):
         return BytesIO(self.conn.Get(pos))