add error status to query-stream

lib/query-stream.js

@@ -27,6 +27,7 @@ class QueryStream extends Readable {
     this.destroyed = false
     this.inflight = 0
     this.responses = 0
+    this.errors = 0
     this.updates = 0
     this.table = opts.table || new QueryTable(node.id, target)
 
@@ -64,6 +65,7 @@ class QueryStream extends Readable {
     }
 
     if (err) {
+      this.errors++
       this.emit('warning', err)
       this._readMaybe()
       return