Svelte 5: using inlang Paraglide JS message in <svelte:head> meta description tag causes error in SSR

[henrikvilhelmberglund]

Describe the bug

Svelte 5: using inlang Paraglide JS message in svelte:head meta description tag causes error in SSR.

Eg. this:

<svelte:head>
  <meta name="description" content="{m.title()}" />
</svelte:head>

The error is the following:

Uncaught (in promise) Svelte error: svelte_component_invalid_this_value
The `this={...}` property of a `<svelte:component>` must be a Svelte component, if defined

The error started appearing in 5.0.0-next.179. Changing the version to 5.0.0-next.178 makes it work again, also disabling SSR makes it work.

Reproduction

Paraglide doesn't run on Stackblitz so the repro needs to be cloned.
Repro: https://github.com/henrikvilhelmberglund/svelte-inlang-repro
Working: Change branch to working or just install 5.0.0-next.178.

Logs

(in browser)
Uncaught (in promise) Svelte error: svelte_component_invalid_this_value
The `this={...}` property of a `<svelte:component>` must be a Svelte component, if defined
    at svelte_component_invalid_this_value (http://localhost:5174/node_modules/.vite/deps/chunk-2WU4MH3N.js?v=bc39b3ac:196:19)
    at Module.validate_dynamic_component (http://localhost:5174/node_modules/.vite/deps/chunk-ZVJJQCF7.js?v=bc39b3ac:2785:7)
    at http://localhost:5174/@fs/C:/Github/repros/svelte-inlang-repro/.svelte-kit/generated/root.svelte:84:11
    at http://localhost:5174/node_modules/.vite/deps/chunk-ZVJJQCF7.js?v=bc39b3ac:949:30
    at update_reaction (http://localhost:5174/node_modules/.vite/deps/chunk-2WU4MH3N.js?v=bc39b3ac:1038:23)
    at update_effect (http://localhost:5174/node_modules/.vite/deps/chunk-2WU4MH3N.js?v=bc39b3ac:1156:21)
    at create_effect (http://localhost:5174/node_modules/.vite/deps/chunk-2WU4MH3N.js?v=bc39b3ac:274:7)
    at branch (http://localhost:5174/node_modules/.vite/deps/chunk-2WU4MH3N.js?v=bc39b3ac:396:10)
    at http://localhost:5174/node_modules/.vite/deps/chunk-ZVJJQCF7.js?v=bc39b3ac:949:17
    at update_reaction (http://localhost:5174/node_modules/.vite/deps/chunk-2WU4MH3N.js?v=bc39b3ac:1038:23)Svelte error: svelte_component_invalid_this_value
The `this={...}` property of a `<svelte:component>` must be a Svelte component, if defined
    at svelte_component_invalid_this_value (http://localhost:5174/node_modules/.vite/deps/chunk-2WU4MH3N.js?v=bc39b3ac:196:19)
    at Module.validate_dynamic_component (http://localhost:5174/node_modules/.vite/deps/chunk-ZVJJQCF7.js?v=bc39b3ac:2785:7)
    at http://localhost:5174/@fs/C:/Github/repros/svelte-inlang-repro/.svelte-kit/generated/root.svelte:84:11
    at http://localhost:5174/node_modules/.vite/deps/chunk-ZVJJQCF7.js?v=bc39b3ac:949:30
    at update_reaction (http://localhost:5174/node_modules/.vite/deps/chunk-2WU4MH3N.js?v=bc39b3ac:1038:23)
    at update_effect (http://localhost:5174/node_modules/.vite/deps/chunk-2WU4MH3N.js?v=bc39b3ac:1156:21)
    at create_effect (http://localhost:5174/node_modules/.vite/deps/chunk-2WU4MH3N.js?v=bc39b3ac:274:7)
    at branch (http://localhost:5174/node_modules/.vite/deps/chunk-2WU4MH3N.js?v=bc39b3ac:396:10)
    at http://localhost:5174/node_modules/.vite/deps/chunk-ZVJJQCF7.js?v=bc39b3ac:949:17
    at update_reaction (http://localhost:5174/node_modules/.vite/deps/chunk-2WU4MH3N.js?v=bc39b3ac:1038:23)

System Info

System:
    OS: Windows 10 10.0.19045
    CPU: (8) x64 Intel(R) Core(TM) i7-2600K CPU @ 3.40GHz
    Memory: 837.46 MB / 15.95 GB
  Binaries:
    Node: 20.14.0 - C:\Program Files\nodejs\node.EXE
    Yarn: 1.22.22 - C:\Program Files\nodejs\yarn.CMD
    npm: 10.7.0 - C:\Program Files\nodejs\npm.CMD
    bun: 1.1.18 - ~\.bun\bin\bun.EXE
  Browsers:
    Edge: Chromium (126.0.2592.102)
    Internet Explorer: 11.0.19041.4355
  npmPackages:
    svelte: 5.0.0-next.185 => 5.0.0-next.185

Severity

blocking an upgrade