When you choose def.confirm and answer "No", template creation is interrupted.

[gremo]

VS Code 1.45.1, template tsconfig.json (shipped with this extension):

If you choose "No", the actual file is not created:

Template source:

{{#def.select('MODULE', 'Specify module code generation', ['none','commonjs','amd','system','umd','es6','es2015','esnext'])}}
{{#def.select('TARGET', 'Specify ECMAScript target version', ['es3','es6','es2016','es2017','esnext'])}}
{{#def.confirm('SOURCE_MAP', 'Should generate corresponding .map file?')}}
{
  "compilerOptions": {
      "module": "{{=$.MODULE}}",
      "target": "{{=$.TARGET}}",
      "sourceMap": {{=$.SOURCE_MAP}}
  },
  "exclude": [
      "node_modules"
  ]
}