fix: check client type at runtime instead of in flow

flow-typed/npm/apollo-client_v2.x.x.js

@@ -1,9 +1,20 @@
 // flow-typed signature: ae6dd2fff7718a6434052f6830bf129b
 // flow-typed version: 2cbae06e0e/apollo-client_v2.x.x/flow_>=v0.57.x
 
-import type {DocumentNode, ExecutionResult, GraphQLError} from 'graphql';
-
 declare module "apollo-client" {
+  /**
+   * Types From graphql
+   * graphql types are maintained in the graphql-js repo
+   */
+  declare type DocumentNode = any;
+  declare type ExecutionResult<T> = {
+    data?: T,
+    extensions?: { [string]: any },
+    errors?: any[]
+  };
+  declare type GraphQLError = any;
+  /** End From graphql */
+
   declare type OperationVariables = { [key: string]: any };
 
   declare export function print(ast: any): string;
@@ -62,7 +73,6 @@ declare module "apollo-client" {
     mutationStore: MutationStore;
     queryStore: QueryStore;
     dataStore: DataStore<TStore>;
-    queries: Map<string, {document: DocumentNode, observableQuery: ObservableQuery<any>}>;
 
     constructor({
       link: ApolloLink,

src/index.js

@@ -1,6 +1,6 @@
 // @flow
 
-import type {ApolloClient} from 'apollo-client'
+import {ApolloClient} from 'apollo-client'
 import getSchemaTypes from './getSchemaTypes'
 import type {Types} from './getSchemaTypes'
 import doesQueryContain from './doesQueryContain'
@@ -21,11 +21,15 @@ function every<T>(array: $ReadOnlyArray<T>, predicate: (elem: T) => boolean): bo
 }
 
 export default async function refetch(
-  client: ApolloClient<any>,
+  client: mixed,
   typenameOrTerms: string | $ReadOnlyArray<Term>,
   ids?: ?any,
   idField?: string
 ): Promise<any> {
+  if (!(client instanceof ApolloClient)) throw new Error(
+    `client must be an ApolloClient, instead got: ${String(client)}`
+  )
+
   const types: Types = await getSchemaTypes(client)
 
   let terms