Take absence of information as a difference, after all

Is '5 main street' same as 'main street'? Probably not. It may be that
less detailed data is different data, not just bad data. maybe this can
be changed if coordinates are considered, too.

middleware/dedupe.js

@@ -96,10 +96,6 @@ function propMatch(item1, item2, prop) {
     prop2= prop2[0];
   }
 
-  if (!prop1 || !prop2) {
-    return; // absence of information does not make an item different
-  }
-
   if (normalizeString(prop1) !== normalizeString(prop2)) {
     throw new Error('different');
   }