fix: check PluralRules & RelativeTimeFormat lazily instead

fixes #1487

examples/index.tsx

@@ -1,6 +1,5 @@
 import 'core-js/stable';
 import '@formatjs/intl-pluralrules/polyfill';
-import '@formatjs/intl-relativetimeformat/polyfill';
 import * as React from 'react';
 import * as ReactDOM from 'react-dom';
 import Timezone from './TimeZone';

src/components/relative.tsx

@@ -3,7 +3,7 @@
  * Copyrights licensed under the New BSD License.
  * See the accompanying LICENSE file for terms.
  */
-
+import '@formatjs/intl-relativetimeformat/polyfill';
 import * as React from 'react';
 import {Context} from './injectIntl';
 import {FormatRelativeTimeOptions} from '../types';

src/formatters/plural.ts

@@ -12,6 +12,13 @@ export function formatPlural(
   value: Parameters<IntlFormatters['formatPlural']>[0],
   options: Parameters<IntlFormatters['formatPlural']>[1] = {}
 ) {
+  if (!Intl.PluralRules) {
+    onError(
+      createError(`Intl.PluralRules is not available in this environment.
+Try polyfilling it using "@formatjs/intl-pluralrules"
+`)
+    );
+  }
   let filteredOptions = filterProps(options, PLURAL_FORMAT_OPTIONS);
 
   try {

src/formatters/relativeTime.ts

@@ -39,6 +39,14 @@ export function formatRelativeTime(
   if (!unit) {
     unit = 'second';
   }
+  const RelativeTimeFormat = (Intl as any).RelativeTimeFormat;
+  if (!RelativeTimeFormat) {
+    config.onError(
+      createError(`Intl.RelativeTimeFormat is not available in this environment.
+Try polyfilling it using "@formatjs/intl-relativetimeformat"
+`)
+    );
+  }
   try {
     return getFormatter(config, getRelativeTimeFormat, options).format(
       value,

src/utils.ts

@@ -112,16 +112,6 @@ export function createIntlCache(): IntlCache {
  */
 export function createFormatters(cache: IntlCache = createIntlCache()) {
   const RelativeTimeFormat = (Intl as any).RelativeTimeFormat;
-  if (!RelativeTimeFormat) {
-    throw new Error(`Intl.RelativeTimeFormat is not available in this environment.
-Try polyfilling it using "@formatjs/intl-relativetimeformat"
-`);
-  }
-  if (!Intl.PluralRules) {
-    throw new Error(`Intl.PluralRules is not available in this environment.
-Try polyfilling it using "@formatjs/intl-pluralrules"
-`);
-  }
   return {
     getDateTimeFormat: memoizeIntlConstructor(
       Intl.DateTimeFormat,