fix(legacy): allow mutil i18n instance for bridge (#983)

Author: kazupon

packages/vue-i18n-core/src/i18n.ts

@@ -93,7 +93,6 @@ declare module 'vue' {
 
 // for bridge
 let _legacyVueI18n: any = /* #__PURE__*/ null // eslint-disable-line @typescript-eslint/no-explicit-any
-let _legacyI18n: I18n | null = /* #__PURE__*/ null // eslint-disable-line @typescript-eslint/no-explicit-any
 
 /**
  * I18n Options for `createI18n`
@@ -471,11 +470,6 @@ export function createI18n<
 export function createI18n(options: any = {}, VueI18nLegacy?: any): any {
   type _I18n = I18n & I18nInternal
 
-  if (__BRIDGE__ && _legacyI18n) {
-    __DEV__ &&
-      warn(getWarnMessage(I18nWarnCodes.NOT_SUPPORT_MULTI_I18N_INSTANCE))
-    return _legacyI18n
-  }
   if (__BRIDGE__) {
     _legacyVueI18n = VueI18nLegacy
   }
@@ -675,7 +669,6 @@ export function createI18n(options: any = {}, VueI18nLegacy?: any): any {
       key =>
         Object.defineProperty(i18n, key, { value: (methodMap as any)[key] }) // eslint-disable-line @typescript-eslint/no-explicit-any
     )
-    _legacyI18n = i18n
     return i18n
   }
 }
@@ -783,7 +776,7 @@ export function useI18n<
   }
 
   if (__BRIDGE__) {
-    if (_legacyVueI18n == null || _legacyI18n == null) {
+    if (_legacyVueI18n == null) {
       throw createI18nError(I18nErrorCodes.NOT_INSLALLED)
     }
   }
@@ -936,10 +929,7 @@ function getI18nInstance(instance: ComponentInternalInstance): I18n {
     if (vm == null) {
       throw createI18nError(I18nErrorCodes.UNEXPECTED_ERROR)
     }
-    let i18n = (vm as any)._i18nBridgeRoot // eslint-disable-line @typescript-eslint/no-explicit-any
-    if (!i18n) {
-      i18n = _legacyI18n
-    }
+    const i18n = (vm as any)._i18nBridgeRoot // eslint-disable-line @typescript-eslint/no-explicit-any
     /* istanbul ignore if */
     if (!i18n) {
       throw createI18nError(I18nErrorCodes.NOT_INSLALLED)

packages/vue-i18n-core/src/warnings.ts

@@ -11,8 +11,7 @@ export const I18nWarnCodes = {
   NOT_SUPPORTED_PRESERVE_DIRECTIVE: inc(), // 10
   NOT_SUPPORTED_GET_CHOICE_INDEX: inc(), // 11
   COMPONENT_NAME_LEGACY_COMPATIBLE: inc(), // 12
-  NOT_FOUND_PARENT_SCOPE: inc(), // 13
-  NOT_SUPPORT_MULTI_I18N_INSTANCE: inc() // 14
+  NOT_FOUND_PARENT_SCOPE: inc() // 13
 } as const
 
 type I18nWarnCodes = typeof I18nWarnCodes[keyof typeof I18nWarnCodes]
@@ -24,8 +23,7 @@ export const warnMessages: { [code: number]: string } = {
   [I18nWarnCodes.NOT_SUPPORTED_PRESERVE_DIRECTIVE]: `Not supported 'preserveDirectiveContent'.`,
   [I18nWarnCodes.NOT_SUPPORTED_GET_CHOICE_INDEX]: `Not supported 'getChoiceIndex'.`,
   [I18nWarnCodes.COMPONENT_NAME_LEGACY_COMPATIBLE]: `Component name legacy compatible: '{name}' -> 'i18n'`,
-  [I18nWarnCodes.NOT_FOUND_PARENT_SCOPE]: `Not found parent scope. use the global scope.`,
-  [I18nWarnCodes.NOT_SUPPORT_MULTI_I18N_INSTANCE]: `Not support multi i18n instance.`
+  [I18nWarnCodes.NOT_FOUND_PARENT_SCOPE]: `Not found parent scope. use the global scope.`
 }
 
 export function getWarnMessage(