Fix #274 (#280)

* Fix #274

* added changeset

Co-authored-by: Dotan Simha <[email protected]>

Author: kamilkisiela

.changeset/pink-countries-know.md

@@ -0,0 +1,5 @@
+---
+'@graphql-eslint/eslint-plugin': patch
+---
+
+fix for `no-unreachable-types` does not recognize implemented interfaces

packages/plugin/src/graphql-ast.ts

@@ -82,10 +82,7 @@ export function collectReachableTypes(schema: GraphQLSchema): Set<string> {
 
   function collectFromInterfaces(interfaces: GraphQLInterfaceType[]): void {
     if (interfaces) {
-      interfaces.forEach(interfaceType => {
-        collectFromFieldMap(interfaceType.getFields());
-        collectFromInterfaces(interfaceType.getInterfaces());
-      });
+      interfaces.forEach(collectFrom);
     }
   }