Error when running dev server: No known conditions for "./action" specifier in "svelte" package [plugin vite:dep-scan]

[MathiasWP]

Describe the bug

In one of our components we type import ActionReturn from svelte/action:

import { type ActionReturn } from 'svelte/action';

When running pnpm dev on our SvelteKit project we get the following error in the terminal:

✘ [ERROR] No known conditions for "./action" specifier in "svelte" package [plugin vite:dep-scan]

script:/frontend/apps/kvist/src/ui/components/KvistPopover/KvistPopover.svelte?id=0:70:7:
  70 │ import 'svelte/action'
	 ╵        ~~~~~~~~~~~~~~~

This error came from the "onResolve" callback registered here:

../../node_modules/.pnpm/[email protected]/node_modules/esbuild/lib/main.js:1150:20:
  1150 │       let promise = setup({
	   ╵                     ^

at setup (file:///frontend/node_modules/.pnpm/[email protected]_@[email protected][email protected][email protected][email protected][email protected]/node_modules/vite/dist/node/chunks/dep-CfG9u7Cn.js:18418:13)
at handlePlugins (/frontend/node_modules/.pnpm/[email protected]/node_modules/esbuild/lib/main.js:1150:21)
at buildOrContextImpl (/frontend/node_modules/.pnpm/[email protected]/node_modules/esbuild/lib/main.js:873:5)
at Object.buildOrContext (/frontend/node_modules/.pnpm/[email protected]/node_modules/esbuild/lib/main.js:699:5)
at /frontend/node_modules/.pnpm/[email protected]/node_modules/esbuild/lib/main.js:2038:68
at new Promise (<anonymous>)
at Object.context (/frontend/node_modules/.pnpm/[email protected]/node_modules/esbuild/lib/main.js:2038:27)
at Object.context (/frontend/node_modules/.pnpm/[email protected]/node_modules/esbuild/lib/main.js:1880:58)
at prepareEsbuildScanner (file:///frontend/node_modules/.pnpm/[email protected]_@[email protected][email protected][email protected][email protected][email protected]/node_modules/vite/dist/node/chunks/dep-CfG9u7Cn.js:18206:24)

This error seems to be a kind error, as everything works as expected, but it's a little unlucky to get this error every time we boot up our dev-server.

Reproduction

https://github.com/MathiasWP/no-known-condition-for-action

Logs

System Info

System:
    OS: macOS 15.2
    CPU: (8) arm64 Apple M1 Pro
    Memory: 966.75 MB / 16.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 23.6.1 - /opt/homebrew/bin/node
    npm: 10.9.2 - /opt/homebrew/bin/npm
    pnpm: 10.1.0 - /opt/homebrew/bin/pnpm
    bun: 1.0.0 - ~/.bun/bin/bun
  Browsers:
    Brave Browser: 131.1.73.104
    Chrome: 132.0.6834.160
    Edge: 132.0.2957.140
    Safari: 18.2
  npmPackages:
    svelte: ^5.19.9 => 5.19.9

Severity

annoyance

[jasonlyu123]

With TypeScript's verbatimModuleSyntax compiler option,

import { type xx } from "module"

is transformed into

 import "module"

But svelte/action is a type-only module and doesn't exist in the runtime, svelte/elements also. You can write import type to avoid the problem. To make it work with import { type } Svelte needs to actually create an empty module for this but I am not sure this makes sense.

import type { xx } from "module"

[Conduitry]

Hm. Yeah, I don't know whether Svelte should publish dummy JS modules for these types-only modules. I can see there are cases where it would result in fewer confusing errors, but it also feels icky. I dunno.

[Ocean-OS]

This is also a bit icky, but could the compiler just remove these imports from the component if they are from one of Svelte's type-only modules?