feat: better taskfile cycle error handling

errors/errors.go

@@ -20,6 +20,7 @@ const (
 	CodeTaskfileVersionCheckError
 	CodeTaskfileNetworkTimeout
 	CodeTaskfileDuplicateInclude
+	CodeTaskfileCycle
 )
 
 // Task related exit codes

errors/errors_taskfile.go

@@ -191,3 +191,21 @@ func (err *TaskfileDuplicateIncludeError) Error() string {
 func (err *TaskfileDuplicateIncludeError) Code() int {
 	return CodeTaskfileDuplicateInclude
 }
+
+// TaskfileCycleError is returned when we detect that a Taskfile includes a
+// set of Taskfiles that include each other in a cycle.
+type TaskfileCycleError struct {
+	Source      string
+	Destination string
+}
+
+func (err TaskfileCycleError) Error() string {
+	return fmt.Sprintf("task: include cycle detected between %s <--> %s",
+		err.Source,
+		err.Destination,
+	)
+}
+
+func (err TaskfileCycleError) Code() int {
+	return CodeTaskfileCycle
+}

taskfile/reader.go

@@ -153,6 +153,12 @@ func (r *Reader) include(node Node) error {
 					Namespaces:  []string{namespace, edge.Properties.Data.(*ast.Include).Namespace},
 				}
 			}
+			if errors.Is(err, graph.ErrEdgeCreatesCycle) {
+				return errors.TaskfileCycleError{
+					Source:      node.Location(),
+					Destination: includeNode.Location(),
+				}
+			}
 			return err
 		})
 		return nil