as_tbl_graph doesn't return a tbl_graph for data.tree::Node

[oliverbeagley]

Looks like the method for Node doesn't re-class after converting to igraph https://github.com/thomasp85/tidygraph/blob/master/R/data_tree.R#L8

library(data.tree)
library(tidygraph)
#> 
#> Attaching package: 'tidygraph'
#> The following object is masked from 'package:stats':
#> 
#>     filter

data(acme)

gr <- as_tbl_graph(acme)
gr
#> IGRAPH 5e514fb DN-- 11 10 -- 
#> + attr: name (v/c)
#> + edges from 5e514fb (vertex names):
#>  [1] Acme Inc. ->Accounting              
#>  [2] Acme Inc. ->Research                
#>  [3] Acme Inc. ->IT                      
#>  [4] Accounting->New Software            
#>  [5] Accounting->New Accounting Standards
#>  [6] Research  ->New Product Line        
#>  [7] Research  ->New Labs                
#>  [8] IT        ->Outsource               
#> + ... omitted several edges

as_tbl_graph(gr)
#> # A tbl_graph: 11 nodes and 10 edges
#> #
#> # A rooted tree
#> #
#> # Node Data: 11 x 1 (active)
#>   name                    
#>   <chr>                   
#> 1 Acme Inc.               
#> 2 Accounting              
#> 3 New Software            
#> 4 New Accounting Standards
#> 5 Research                
#> 6 New Product Line        
#> # … with 5 more rows
#> #
#> # Edge Data: 10 x 2
#>    from    to
#>   <int> <int>
#> 1     1     2
#> 2     1     5
#> 3     1     8
#> # … with 7 more rows

^{Created on 2019-10-23 by the reprex package (v0.3.0)}