In 2021.2.0b7, new URP project from template, build for WebGL fails with this:
Building Library\Bee\artifacts\WebGL\build\debug_WebGL_wasm\build.js failed with output:
emcc:WARNING: --llvm-lto ignored when using llvm backend
emcc2: error: '--js-library': file not found: 'Packages/com.unity.analytics/Plugins/WindowUtil.jslib'
The solution is to open Package Manager and remove the Analytics Library (currently 3.5.3).