refactor(debug): Rewrite error message

demo/src/views/B.js

@@ -35,4 +35,4 @@ export default class Test extends React.Component {
       <div>This is b.</div>
     );
   }
-}
\ No newline at end of file
+}

src/components/Consumer.tsx

 import React from 'react';
 import Comment from './Comment';
 import {LIFECYCLE, ICache, ICacheItem} from './Provider';
+import {warn} from '../utils/debug';
 import findDOMNodeByFiberNode from '../utils/findDOMNodeByFiberNode';
 import createUniqueIdentification from '../utils/createUniqueIdentification';
 
@@ -25,7 +26,7 @@ class Consumer extends React.PureComponent<IConsumerProps> {
     super(props, ...args);
     const {cache, setCache, children} = props;
     if (!cache || !setCache) {
-      throw new Error('<KeepAlive> component must be in the <Provider> component.');
+      warn('[React Keep Alive] <KeepAlive> component must be in the <Provider> component.');
     }
     React.Children.only(children);
   }

src/components/Provider.tsx

@@ -3,6 +3,7 @@ import ReactDOM from 'react-dom';
 import Comment from './Comment';
 import KeepAliveContext from '../contexts/KeepAliveContext';
 import createEventEmitter from '../utils/createEventEmitter';
+import {warn} from '../utils/debug';
 import createUniqueIdentification from '../utils/createUniqueIdentification';
 import createStoreElement from '../utils/createStoreElement';
 
@@ -88,7 +89,7 @@ export default class KeepAliveProvider extends React.PureComponent<IKeepAlivePro
     const currentCache = cache[identification];
     const key = currentCache && currentCache.key;
     if (key && value.key && key !== (value.key as unknown)) {
-      throw new Error('Cached components have duplicates.');
+      warn('[React Keep Alive] Cached components have duplicates.');
     }
     if (!currentCache) {
       keys.push(identification);

src/utils/createEventEmitter.ts

+import {warn} from './debug';
+
 type EventNames = string | string[];
 
 type Listener = (...args: any) => void;
@@ -17,7 +19,7 @@ export default function createEventEmitter() {
       current = current[key];
     }
     if (!Array.isArray(current)) {
-      throw new Error('Access path error.');
+      warn('[React Keep Alive] Access path error.');
     }
     if (direction) {
       current.unshift(listener);
@@ -82,7 +84,7 @@ export default function createEventEmitter() {
 
   function getEventNames(eventNames: EventNames): string[] {
     if (!eventNames) {
-      throw new Error('Must exist event name.');
+      warn('[React Keep Alive] Must exist event name.');
     }
     if (typeof eventNames === 'string') {
       eventNames = [eventNames];

src/utils/debug.ts

+type Warn = (message?: string) => void;
+
+export let warn: Warn = () => undefined;
+
+if (process.env.NODE_ENV !== 'production') {
+  /**
+   * Prints a warning in the console if it exists.
+   *
+   * @param {*} message
+   */
+  warn = message => {
+    if (typeof console !== undefined && typeof console.error === 'function') {
+      console.error(message);
+    } else {
+      throw new Error(message);
+    }
+  };
+}

src/utils/keepAlive.tsx

@@ -5,6 +5,7 @@ import Consumer from '../components/Consumer';
 import {START_MOUNTING_DOM, LIFECYCLE} from '../components/Provider';
 import md5 from './md5';
 import noop from './noop';
+import {warn} from './debug';
 import getContextIdentificationByFiberNode from './getContextIdentificationByFiberNode';
 import withIdentificationContextConsumer, {IIdentificationContextComponentProps} from './withIdentificationContextConsumer';
 import withKeepAliveContextConsumer, {IKeepAliveContextComponentProps} from './withKeepAliveContextConsumer';
@@ -65,7 +66,7 @@ export default function keepAliveDecorator({
     const displayName = (name || getDisplayName(Component)) as any;
 
     if (!displayName) {
-      throw new Error('Each component must have a name, which can be the component\'s displayName or name static property. You can also configure name when keepAlive decorates the component.');
+      warn('[React Keep Alive] Each component must have a name, which can be the component\'s displayName or name static property. You can also configure name when keepAlive decorates the component.');
     }
 
     Component.prototype.componentDidMount = function () {