fix: properly use indentedSyntax for sass files

Fixes #159

Author: kevinmarrec

src/sass.ts

@@ -12,6 +12,10 @@ export default function setupSass (this: ModuleThis, options: Pick<Options, 'cus
     this.options.build!.loaders.scss.implementation =
       dartSass
 
+  // Ensure it uses indented syntax for Sass files
+  this.options.build!.loaders.sass.sassOptions = this.options.build!.loaders.sass.sassOptions || {}
+  this.options.build!.loaders.sass.sassOptions.indentedSyntax = true
+
   // Custom variables
   if (options.customVariables && options.customVariables.length > 0) {
     const imports = options.customVariables.map(path => `@import '${path}'`).join('\n')

test/module.test.ts

@@ -87,6 +87,7 @@ describe('setupSass', () => {
 
     expect(nuxt.options.build.loaders.sass.indentedSyntax).toBeUndefined()
     expect(nuxt.options.build.loaders.sass.implementation).toEqual(dartSass)
+    expect(nuxt.options.build.loaders.sass.sassOptions.indentedSyntax).toBe(true)
     expect(nuxt.options.build.loaders.scss.implementation).toEqual(dartSass)
   })