optional chaining for graphql-language-service@5.0.0 breaks upstream build

Hi,

We are using graphiql module in our app which takes the latest of 1.x.x version and since upgrading recently to 1.7.1 building graphql-language-service@5.0.0 is failing with the following reason:

16:39:07  Module parse failed: Unexpected token (45:28)
16:39:07  You may need an appropriate loader to handle this file type, currently no loaders are configured to process this file. See https://webpack.js.org/concepts#loaders
16:39:07  |     if (kind === RuleKinds.IMPLEMENTS ||
16:39:07  |         (kind === RuleKinds.NAMED_TYPE &&
16:39:07  >             state.prevState?.kind === RuleKinds.IMPLEMENTS)) {
16:39:07  |         return getSuggestionsForImplements(token, state, schema, queryText, typeInfo);
16:39:07  |     }
16:39:07   @ ../node_modules/apiconnect-explorer/node_modules/graphql-language-service/esm/interface/index.js 2:0-45 2:0-45
16:39:07   @ ../node_modules/apiconnect-explorer/node_modules/graphql-language-service/esm/index.js
16:39:07   @ ../node_modules/apiconnect-explorer/node_modules/graphiql/esm/components/GraphiQL.js
16:39:07   @ ../node_modules/apiconnect-explorer/node_modules/graphiql/esm/index.js
16:39:07   @ ../node_modules/apiconnect-explorer/dist/es/components/TestToolGraphQL.js
16:39:07   @ ../node_modules/apiconnect-explorer/dist/es/components/GraphQLDisplay.js
16:39:07   @ ../node_modules/apiconnect-explorer/dist/es/components/Routing.js
16:39:07   @ ../node_modules/apiconnect-explorer/dist/es/App.js
16:39:07   @ ../node_modules/apiconnect-explorer/dist/es/Bootstrap.js

similar issue https://github.com/graphql/graphiql/issues/1852, but we are using webpack 4.x and babel 6.x, so wondering if it is something we need to resolve on our end by doing something like https://danw1ld.medium.com/optional-chaining-for-javascript-with-babel-7-and-webpack-4-2de8fd9dbdd5 to handle optional chaining or it can be resolved from the module itself?

[edwinckc]

It looks like we’re still getting the same error on 1.7.2, with graphql-language-service "^5.0.1" 🤔

[acao]

every library from this repo that is universal or browser centric should use target es6 with typescript by default, which should not include optional chaining, as that is equivalent to es2015. we only override target to a later version for the LSP server, vscode-graphql and CLI, so there is something we are doing wrong here