Fix API Bug (fail on empty assignees)

models/issue_assignees.go

@@ -5,6 +5,7 @@
 package models
 
 import (
+	"code.gitea.io/gitea/modules/util"
 	"fmt"
 
 	"xorm.io/xorm"
@@ -171,25 +172,31 @@ func toggleUserAssignee(e *xorm.Session, issue *Issue, assigneeID int64) (remove
 // MakeIDsFromAPIAssigneesToAdd returns an array with all assignee IDs
 func MakeIDsFromAPIAssigneesToAdd(oneAssignee string, multipleAssignees []string) (assigneeIDs []int64, err error) {
 
+	var requestAssignees []string
+
 	// Keeping the old assigning method for compatibility reasons
-	if oneAssignee != "" {
+	if !util.ExistsInSlice(oneAssignee, multipleAssignees) {
+		requestAssignees = append(requestAssignees, oneAssignee)
+	}
 
-		// Prevent double adding assignees
-		var isDouble bool
+	//Prevent empty assignerees
+	if util.ExistsInSlice("", multipleAssignees) {
 		for _, assignee := range multipleAssignees {
-			if assignee == oneAssignee {
-				isDouble = true
-				break
+			if assignee == "" {
+				continue
 			}
+			requestAssignees = append(requestAssignees, assignee)
 		}
-
-		if !isDouble {
-			multipleAssignees = append(multipleAssignees, oneAssignee)
-		}
+	} else {
+		requestAssignees = append(requestAssignees, multipleAssignees...)
 	}
 
-	// Get the IDs of all assignees
-	assigneeIDs, err = GetUserIDsByNames(multipleAssignees, false)
+	if len(requestAssignees) > 0 {
+		// Get the IDs of all assignees
+		assigneeIDs, err = GetUserIDsByNames(requestAssignees, false)
+	} else {
+		return nil, nil
+	}
 
 	return
 }