fix(entity-mapper): check for existing state on asyncBootstrap

In the rare case of an entity being rendered twice with the same mapper,
in the old situation this would cause the component from being loaded
twice. Now, before loading, we check if there was already a state.

Author: Ian Wensink

src/components/EntityMapper.js

@@ -79,6 +79,17 @@ class EntityMapper extends Component {
   async asyncBootstrap() {
     const { mapper, asyncMapper } = this.props;
     const { uuid, entityProps } = this.state;
+
+    // If this mapper + uuid combination is already in state, use that state
+    const state = getNested(
+      () =>
+        this.context.hnContext.state.entities.find(
+          e => e.mapper === mapper && e.uuid === uuid,
+        ).componentState,
+    );
+
+    if (state) return true;
+
     this.context.hnContext.state.entities.push({
       componentState: await this.loadComponent({
         asyncMapper,