fix(live): replace panic in live loader with errors (#7798) (#8944)

dgraph/cmd/live/run.go

@@ -324,7 +324,7 @@ func generateQuery(node, predicate, xid string) string {
 	return sb.String()
 }
 
-func (l *loader) upsertUids(nqs []*api.NQuad) {
+func (l *loader) upsertUids(nqs []*api.NQuad) error {
 	// We form upsertPredicate query for each of the ids we saw in the request, along with
 	// adding the corresponding xid to that uid. The mutation we added is only useful if the
 	// uid doesn't exists.
@@ -379,7 +379,7 @@ func (l *loader) upsertUids(nqs []*api.NQuad) {
 	}
 
 	if len(mutations) == 0 {
-		return
+		return nil
 	}
 
 	query.WriteRune('}')
@@ -390,20 +390,26 @@ func (l *loader) upsertUids(nqs []*api.NQuad) {
 		Query:     query.String(),
 		Mutations: []*api.Mutation{{Set: mutations}},
 	})
-	x.Panic(err)
+	if err != nil {
+		return err
+	}
 
 	type dResult struct {
 		Uid string
 	}
 
 	var result map[string][]dResult
-	x.Panic(json.Unmarshal(resp.GetJson(), &result))
+	if err := json.Unmarshal(resp.GetJson(), &result); err != nil {
+		return err
+	}
 
 	for xid, idx := range ids {
 		// xid already exist in dgraph
 		if val, ok := result[idx]; ok && len(val) > 0 {
 			uid, err := strconv.ParseUint(val[0].Uid, 0, 64)
-			x.Panic(err)
+			if err != nil {
+				return err
+			}
 
 			l.alloc.SetUid(xid, uid)
 			continue
@@ -412,12 +418,16 @@ func (l *loader) upsertUids(nqs []*api.NQuad) {
 		// new uid created in dgraph
 		if val, ok := resp.GetUids()[generateUidFunc(idx)]; ok {
 			uid, err := strconv.ParseUint(val, 0, 64)
-			x.Panic(err)
+			if err != nil {
+				return err
+			}
 
 			l.alloc.SetUid(xid, uid)
 			continue
 		}
 	}
+
+	return nil
 }
 
 // allocateUids looks for the maximum uid value in the given NQuads and bumps the
@@ -540,7 +550,9 @@ func (l *loader) processLoadFile(ctx context.Context, rd *bufio.Reader, ck chunk
 				// figure out its processing.
 				// Currently, this option works with data loading in the logged-in namespace.
 				// TODO(Naman): Add a test for a case when it works and when it doesn't.
-				l.upsertUids(nqs)
+				if err := l.upsertUids(nqs); err != nil {
+					return
+				}
 			}
 
 			for _, nq := range nqs {