fix #97 - insular instances on graph

CHANGELOG.md

@@ -18,6 +18,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Display plain Pleroma version rather than the Mastodon-compatible string
+- Fix some insular instances appearing on the graph
 
 ### Security
 

backend/lib/backend/api.ex

@@ -75,6 +75,8 @@ defmodule Backend.Api do
     user_threshold = get_config(:personal_instance_threshold)
 
     Instance
+    # filter down to instances that have edges
+    |> join(:inner, [i], e in Edge, on: i.domain == e.source_domain or i.domain == e.target_domain)
     |> where(
       [i],
       not is_nil(i.x) and not is_nil(i.y) and not is_nil(i.user_count) and