"Unexpected token 'indent'" when using pug template

[aleksejevski]

Expected behavior

These two templates should work the same as each other:

<template lang="pug">
  .randomContentGen`
    input(v-model="randomContent",disabled)
    button(@click="randomContentGen") Generate Content!!
</template>

<template lang="pug">
.randomContentGen
    input(v-model="randomContent",disabled)`
    button(@click="randomContentGen") Generate Content!!`
</template>

(There is no tab/space at the beginning of the first line inside the second template, but 2 inside the first template.)

Actual behavior

Only the second template can be complied. When using the first template, the second line of which starts with a tab(2 spaces), an exception is thrown on my console:

�   (vue plugin) F:\rollup-vue-test\src\components\randomContentGen.vue:2:1`
    1|
  > 2|   .randomContentGen
-------^
    3|     input(v-model="randomContent",disabled)`
    4|     button(@click="randomContentGen") Generate Content!!`
    5|

unexpected token "indent"

Steps to reproduce the behavior