fix: cycles in tasks array when memory caching was enabled

Resolves #1119

go.mod

@@ -104,6 +104,7 @@ require (
 	github.com/hashicorp/go-multierror v1.1.0 // indirect
 	github.com/hashicorp/hcl v1.0.0 // indirect
 	github.com/inconshreveable/mousetrap v1.0.0 // indirect
+	github.com/jinzhu/copier v0.3.5 // indirect
 	github.com/josharian/intern v1.0.0 // indirect
 	github.com/json-iterator/go v1.1.12 // indirect
 	github.com/lithammer/shortuuid/v3 v3.0.4 // indirect

go.sum

@@ -467,6 +467,8 @@ github.com/jackc/puddle v0.0.0-20190608224051-11cab39313c9/go.mod h1:m4B5Dj62Y0f
 github.com/jackc/puddle v1.1.3/go.mod h1:m4B5Dj62Y0fbyuIc15OsIqK0+JU8nkqQjsgx7dvjSWk=
 github.com/jackc/puddle v1.2.1/go.mod h1:m4B5Dj62Y0fbyuIc15OsIqK0+JU8nkqQjsgx7dvjSWk=
 github.com/jeffbean/tail v1.0.1/go.mod h1:+MhJ+VPZMpv8Ui6WRzpJFuWFKxBCZgVOo5HAmlw1sFc=
+github.com/jinzhu/copier v0.3.5 h1:GlvfUwHk62RokgqVNvYsku0TATCF7bAHVwEXoBh3iJg=
+github.com/jinzhu/copier v0.3.5/go.mod h1:DfbEm0FYsaqBcKcFuvmOZb218JkPGtvSHsKg8S8hyyg=
 github.com/joho/godotenv v1.3.0/go.mod h1:7hK45KPybAkOC6peb+G5yklZfMxEjkZhHbwpqxOKXbg=
 github.com/joho/godotenv v1.4.0 h1:3l4+N6zfMWnkbPEXKng2o2/MR5mSwTrBih4ZEkkz1lg=
 github.com/joho/godotenv v1.4.0/go.mod h1:f4LDr5Voq0i2e/R5DDNOoa2zzDfwtkZa6DnEwAbqwq4=

pkg/models/tasks.go

@@ -17,6 +17,7 @@
 package models
 
 import (
+	"github.com/jinzhu/copier"
 	"math"
 	"regexp"
 	"sort"
@@ -676,7 +677,13 @@ func addRelatedTasksToTasks(s *xorm.Session, taskIDs []int64, taskMap map[int64]
 			continue
 		}
 		fullRelatedTasks[rt.OtherTaskID].IsFavorite = taskFavorites[rt.OtherTaskID]
-		taskMap[rt.TaskID].RelatedTasks[rt.RelationKind] = append(taskMap[rt.TaskID].RelatedTasks[rt.RelationKind], fullRelatedTasks[rt.OtherTaskID])
+
+		// We're duplicating the other task to avoid cycles as these can't be represented properly in json
+		// and would thus fail with an error.
+		otherTask := &Task{}
+		copier.Copy(otherTask, fullRelatedTasks[rt.OtherTaskID])
+		otherTask.RelatedTasks = nil
+		taskMap[rt.TaskID].RelatedTasks[rt.RelationKind] = append(taskMap[rt.TaskID].RelatedTasks[rt.RelationKind], otherTask)
 	}
 
 	return