feat(client): remove data mutation (#32)

* feat(client): remove data mutation

* chore: address comments and fix some other issues

* chore: send the most recent cache upon subscription

client/lib/source/mock-source.ts

@@ -1,13 +1,13 @@
-import { Observable } from "rxjs";
-import { map } from "rxjs/operators";
-import { Update } from "../types";
-import { Source } from "./source";
-import { RPCResponse } from "./ws-source";
+import { Observable } from 'rxjs'
+import { map } from 'rxjs/operators'
+import { Update } from '../types'
+import { Source } from './source'
+import { RPCResponse } from './ws-source'
 
 export class MockSource<T> implements Source<T> {
-  constructor(private readonly seed: Observable<Update<T>>) {}
+  constructor (private readonly seed: Observable<Update<T>>) { }
 
-  watch$(): Observable<RPCResponse<Update<T>>> {
-    return this.seed.pipe(map((result) => ({ result, jsonrpc: "2.0" })));
+  watch$ (): Observable<RPCResponse<Update<T>>> {
+    return this.seed.pipe(map((result) => ({ result, jsonrpc: '2.0' })))
   }
 }

client/lib/source/poll-source.ts

@@ -1,4 +1,4 @@
-import { BehaviorSubject, concat, from, Observable, of, Subject } from 'rxjs'
+import { BehaviorSubject, concat, from, Observable, of } from 'rxjs'
 import { concatMap, delay, map, skip, switchMap, take, tap } from 'rxjs/operators'
 import { Store } from '../store'
 import { Http, Update } from '../types'

client/lib/source/ws-source.ts

@@ -43,14 +43,6 @@ export interface RPCError extends RPCBase {
 }
 export type RPCResponse<T> = RPCSuccess<T> | RPCError
 
-function isRpcError<Error, Result> (arg: { error: Error } | { result: Result}): arg is { error: Error } {
-  return !!(arg as any).error
-}
-
-function isRpcSuccess<Error, Result> (arg: { error: Error } | { result: Result}): arg is { result: Result } {
-  return !!(arg as any).result
-}
-
 class RpcError {
   code: number
   message: string
@@ -61,4 +53,4 @@ class RpcError {
     this.message = e.message
     this.details = e.data.details
   }
-}
+}