I just upgraded my environment to use latest riot 6.0.4 and webpack 5.X
and now I see that debugger truncates last character of local const\var name
it is related to webpack-cli 4.7.2, also reproducible with webpack 4.8.0 -- latest
all works as expected with webpack-cli 3.3.12

steps to reproduce:

1. take this project
2. update sidebar.riot method
   toggleUser() {
   const abc = { a: 1 }
   this.update({
   showUser: !this.state.showUser
   })
   }
3. build with sequence:
   npm install
   npm audit fix
   npm rebuild
   npx webpack
   npm start
4. browse to http://127.0.0.1:3000,
5. in debugger, set a breakpoint in toggleUser() method
6. observe name of the const abc rendered in debugger as "ab"

to see expected behavior:
update package.json
in "scripts" section
"start": "webpack-dev-server --inline --watch --hot --colors -d --port 3000"
in "devDependencies" section
"webpack-cli": "^3.3.12",

then build with steps above,
debugger shows constant name as it should

Please advise if I'm doing something wrong