# Using preview getting ts errors **URL:** \ **Category:** Questions\ **Created:** [August 26, 2019, 4:21pm UTC](https://forum.babylonjs.com/t/using-preview-getting-ts-errors/5290 "2019-08-26T16:21:00Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![delaneyj](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/delaneyj/32/3148_2.png) [@delaneyj](https://forum.babylonjs.com/u/delaneyj)\ **Post date:** [August 26, 2019, 4:21pm UTC](https://forum.babylonjs.com/t/using-preview-getting-ts-errors/5290/1 "2019-08-26T16:21:00Z")
changed `package.json` from ```auto "@babylonjs/core": "^4.0.3", "@babylonjs/inspector": "^4.0.3", "@babylonjs/loaders": "^4.0.3", "@babylonjs/materials": "^4.0.3", "@babylonjs/serializers": "^4.0.3", ``` to ```auto "@babylonjs/core": "^4.1.0-alpha.16", "@babylonjs/inspector": "^4.1.0-alpha.16", "@babylonjs/loaders": "^4.1.0-alpha.16", "@babylonjs/materials": "^4.1.0-alpha.16", "@babylonjs/serializers": "^4.1.0-alpha.16", ``` Removed node\_modules, even try removing yarn.lock. But seeing a [similar error elsewhere](https://forum.babylonjs.com/t/define-typescript-interface-for-options-of-method-to-make-screenshots/4713/40) per @sebavan’s advice I made sure everything was on the preview version. Seeing this TS error ERROR in ```auto /frontend/src/pkgs/node_modules/@babylonjs/core/Engines/engine.d.ts 2527:5 Subsequent variable declarations must have the same type. Variable 'XRWebGLLayer' must be of type '{ new (ses sion: XRSession, context: WebGLRenderingContext | undefined): XRWebGLLayer; prototype: XRWebGLLayer; }', but here has type '{ new (session: XRSession, context?: WebGLRenderingContext | undefined): XRWebGLLayer; prototype: XRWebGLLayer ; }'. 2525 | framebuffer: WebGLFramebuffer; 2526 | } > 2527 | var XRWebGLLayer: { | ^ 2528 | prototype: XRWebGLLayer; 2529 | new(session: XRSession, context?: WebGLRenderingContext): XRWebGLLayer; 2530 | }; ``` Any ideas? ---
**Author:** ![Deltakosh](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/deltakosh/32/26635_2.png) [@Deltakosh](https://forum.babylonjs.com/u/Deltakosh)\ **Post date:** [August 26, 2019, 4:24pm UTC](https://forum.babylonjs.com/t/using-preview-getting-ts-errors/5290/2 "2019-08-26T16:24:19Z")
Are you importing a webXR type definition somewhere? ---
**Author:** ![delaneyj](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/delaneyj/32/3148_2.png) [@delaneyj](https://forum.babylonjs.com/u/delaneyj)\ **Post date:** [August 26, 2019, 4:27pm UTC](https://forum.babylonjs.com/t/using-preview-getting-ts-errors/5290/3 "2019-08-26T16:27:23Z")
No, search the codebase and don’t see ‘webXR’ anywhere. Here are my devDependicies if that helps ```auto "devDependencies": { "@babylonjs/core": "^4.1.0-alpha.16", "@babylonjs/inspector": "^4.1.0-alpha.16", "@babylonjs/loaders": "^4.1.0-alpha.16", "@babylonjs/materials": "^4.1.0-alpha.16", "@babylonjs/serializers": "^4.1.0-alpha.16", "@fortawesome/fontawesome-pro": "^5.10.1", "@lifeomic/attempt": "^3.0.0", "@types/animejs": "^2.0.2", "@types/faker": "^4.1.5", "@types/lodash": "^4.14.137", "@types/node": "^12.7.1", "@types/node-emoji": "^1.8.1", "@types/splitpanes": "^1.0.0", "@vue/cli-plugin-babel": "^3.10.0", "@vue/cli-plugin-eslint": "^3.10.0", "@vue/cli-plugin-pwa": "^3.10.0", "@vue/cli-plugin-typescript": "^3.10.0", "@vue/cli-service": "^3.10.0", "@vue/eslint-config-prettier": "^5.0.0", "@vue/eslint-config-typescript": "^4.0.0", "animejs": "^3.1.0", "axios": "^0.19.0", "babel-eslint": "^10.0.1", "core-js": "^2.6.5", "deepmerge": "^4.0.0", "eslint": "^5.16.0", "eslint-plugin-prettier": "^3.1.0", "eslint-plugin-vue": "^5.0.0", "faker": "^4.1.0", "fibers": "^4.0.1", "lint-staged": "^8.1.5", "lodash": "^4.17.15", "loglevel": "^1.6.3", "long": "^4.0.0", "milsymbol": "^2.0.0", "moment": "^2.24.0", "node-emoji": "^1.10.0", "npm": "^6.10.3", "prettier": "^1.18.2", "protobufjs": "^6.8.8", "register-service-worker": "^1.6.2", "sass": "^1.22.9", "sass-loader": "^7.1.0", "splitpanes": "^1.14.2", "typeface-roboto": "0.0.54", "typeface-roboto-condensed": "0.0.54", "typeface-roboto-mono": "0.0.54", "typescript": "^3.4.3", "vue": "^2.6.10", "vue-class-component": "^7.0.2", "vue-cli-plugin-vuetify": "^0.6.1", "vue-property-decorator": "^8.1.0", "vue-router": "^3.0.3", "vue-template-compiler": "^2.6.10", "vuetify": "^2.0.0", "vuetify-loader": "^1.2.2", "vuex": "^3.0.1", "vuex-class-component": "^1.9.0", "webpack": "^4.39.1", "worker-loader": "^2.0.0" }, ``` in fact the only place `xr` shows up in the codebase is in engine.d.ts and some yarn.lock hashes (xR,Xr) ---
**Author:** ![Deltakosh](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/deltakosh/32/26635_2.png) [@Deltakosh](https://forum.babylonjs.com/u/Deltakosh)\ **Post date:** [August 26, 2019, 4:31pm UTC](https://forum.babylonjs.com/t/using-preview-getting-ts-errors/5290/4 "2019-08-26T16:31:52Z")
which version of typescript? (pinging @sebavan) ---
**Author:** ![Deltakosh](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/deltakosh/32/26635_2.png) [@Deltakosh](https://forum.babylonjs.com/u/Deltakosh)\ **Post date:** [August 26, 2019, 4:34pm UTC](https://forum.babylonjs.com/t/using-preview-getting-ts-errors/5290/5 "2019-08-26T16:34:21Z")
> [@delaneyj](#): > > XRSession (just in case can you delete your node\_modules folder) ? ---
**Author:** ![delaneyj](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/delaneyj/32/3148_2.png) [@delaneyj](https://forum.babylonjs.com/u/delaneyj)\ **Post date:** [August 26, 2019, 4:37pm UTC](https://forum.babylonjs.com/t/using-preview-getting-ts-errors/5290/6 "2019-08-26T16:37:19Z")
> [@delaneyj](#): > > R Yeah I mentioned at the top I deleted the node\_modules, also tried yarn.lock hoping it was a caching issue. @Deltakosh typescript 3.5.3 ---
**Author:** ![sebavan](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/sebavan/32/57_2.png) [@sebavan](https://forum.babylonjs.com/u/sebavan)\ **Post date:** [August 26, 2019, 5:04pm UTC](https://forum.babylonjs.com/t/using-preview-getting-ts-errors/5290/7 "2019-08-26T17:04:18Z")
Could you share your project ??? This would be way simpler to troubleshoot. ---
**Author:** ![delaneyj](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/delaneyj/32/3148_2.png) [@delaneyj](https://forum.babylonjs.com/u/delaneyj)\ **Post date:** [August 26, 2019, 5:55pm UTC](https://forum.babylonjs.com/t/using-preview-getting-ts-errors/5290/8 "2019-08-26T17:55:50Z")
@sebavan I sent you a pm about this. ---
**Author:** ![delaneyj](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/delaneyj/32/3148_2.png) [@delaneyj](https://forum.babylonjs.com/u/delaneyj)\ **Post date:** [August 26, 2019, 6:05pm UTC](https://forum.babylonjs.com/t/using-preview-getting-ts-errors/5290/9 "2019-08-26T18:05:54Z")
So in trying to find a way to zip up and send the project I found that one of our local libs is symlink’d in and it was using `4.0.3`. For future ludites, make sure ALL versions match or your going to have a bad day. Thank you @Deltakosh and @sebavan! Is there a RubberDucky award for @sebavan? ---
**Author:** ![sebavan](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/sebavan/32/57_2.png) [@sebavan](https://forum.babylonjs.com/u/sebavan)\ **Post date:** [August 26, 2019, 6:12pm UTC](https://forum.babylonjs.com/t/using-preview-getting-ts-errors/5290/10 "2019-08-26T18:12:47Z")
So glad it is this as I was really running out of ideas 🙂 ---
**Author:** ![delaneyj](https://sea2.discourse-cdn.com/flex024/user_avatar/forum.babylonjs.com/delaneyj/32/3148_2.png) [@delaneyj](https://forum.babylonjs.com/u/delaneyj)\ **Post date:** [August 26, 2019, 6:13pm UTC](https://forum.babylonjs.com/t/using-preview-getting-ts-errors/5290/11 "2019-08-26T18:13:06Z")
Symlinks are a hell of a drug