Addressed review comments

workflow/executor.go

@@ -1044,9 +1044,8 @@ func (e *executor) prepareOptionalExprDependencies(
 		dependencyType = dgraph.OptionalDependency
 	}
 
-	// The way that this will work is the current node will depend on the grouped
-	// node to isolate the optional dependencies. The current node will depend on it
-	// with either optional or completion dependencies
+	// Creates a new group node to isolate the optional dependencies.
+	// The current node will depend on the group node with the dependency type set in `dependencyType`.
 	optionalDagNode, err := e.createGroupNode(currentNode, pathInCurrentNode, dag, dependencyType)
 	if err != nil {
 		return err

workflow/yaml_test.go

@@ -195,7 +195,8 @@ func TestBuildWaitOptionalExpr_InvalidExpr(t *testing.T) {
 }
 
 func TestBuildWaitOptionalExpr_InvalidTag(t *testing.T) {
-	// It should never get there outside the unit test.
+	// This code tests an invalid tag used with buildOptionalExpressions that
+	// should not be possible in production code due to other checks.
 	yamlInput := []byte(`!invalid some_expr`)
 	input := assert.NoErrorR[yaml.Node](t)(yaml.New().Parse(yamlInput))
 	_, err := buildOptionalExpression(input, make([]string, 0))