Invalid sourcemap when there's \n in the script block

[hyrious]

Describe the bug

Similar issues #13478 #16615 #9961. But here is a possible minimal reproduction:

Reproduction

Save and run this snippet

import * as svelte from 'svelte/compiler'

const code = `<script>
</script>
`

const { js, css } = svelte.compile(code, {
	filename: 'a.svelte',
})

const _16to8 = (x) => unescape(encodeURIComponent(x))

function sourceMapVisual(name, a) {
	if (!a?.code) return
	let [code, map] = [_16to8(a.code), _16to8(a.map)]
	let url =
    'https://evanw.github.io/source-map-visualization/#' +
    btoa(code.length + '\0' + code + map.length + '\0' + map).replace(/\=+$/, '')
	console.log(name, `\x1b]8;;${url}\x1b\\source-map-visualization\x1b]8;;\x07`, a.map)
}

sourceMapVisual(' JS', js)
sourceMapVisual('CSS', css)

Try to change the code to the following strings:

Single line of code: works fine.

<script>let a = 1</script>

Multi line: The "mappings" field of the imported source map contains invalid data. Invalid VLQ data at index 19: Invalid original column: -1. on Source Map Visualization.

<script>
  // You can put anything here
</script>

Logs

I was trying to integrate svelte in esbuild, while esbuild complains:

▲ [WARNING] Bad "mappings" data in source map at character 95: Invalid original column value: -1 [invalid-source-mappings]

    fixture/App.svelte#sourceMappingURL:1:415:
      1 │ ...ASK,KAAK,WAAU,MAAM,CAAC,OAAO,CAAC,GAAG,CAAC,KAAK;;;CAAI,KAAK,KAAK,CAAC;;;;;AAC7D,CAAC"}
        ╵                                                                                  ~~

  The source map "fixture/App.svelte#sourceMappingURL" was referenced by the file
  "fixture/App.svelte" here:

    fixture/App.svelte:18:21:
      18 │ ...rceMappingURL=data:application/json;charset=utf-8;base64,eyJ2ZXJzaW9uIjozLCJuYW1lcy...
         ╵                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

System Info

  System:
    OS: macOS 26.0.1
    CPU: (8) arm64 Apple M3
    Memory: 1.13 GB / 24.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 22.20.0 - /opt/homebrew/opt/node@22/bin/node
    Yarn: 1.22.22 - /opt/homebrew/bin/yarn
    npm: 10.9.3 - /opt/homebrew/opt/node@22/bin/npm
    pnpm: 10.18.3 - /opt/homebrew/bin/pnpm
    bun: 1.2.23 - /Users/hyrious/.bun/bin/bun
    Deno: 2.5.4 - /opt/homebrew/bin/deno
  npmPackages:
    rollup: ^4.52.5 => 4.52.5
    svelte: ^5.41.1 => 5.41.1

Severity

annoyance