# Errors Every message Backtick can show you, by who says it, with its fix. Every message Backtick can show you, by who says it, with its fix. Your editor and `npm run typecheck` report the first two groups; the third is thrown by your server, per request, before anything reaches the phone; the last by your app. ## From TypeScript ### Argument of type '…' is not assignable to parameter of type 'Spliceable' The splice holds something that can't cross: a function, a class instance, a `Date`. Splice what it's for instead: a `Date` as a string, a function as a client function, `` cs`(n: number) => …` ``. See [what can cross](/docs/thinking-in-backtick#splices). ### Property '…' does not exist on type 'GlobalThis' A script used a name from your server without a `$`. Splice it: `$total`, not `total`. See [splices](/docs/thinking-in-backtick#splices). ### This expression is not callable. Type 'Client<…>' has no call signatures A hook, or another client value, was called in a server component. Hooks belong in a [client component](/docs/thinking-in-backtick#client-components). ### JSX element type '…' does not have any construct or call signatures A client component was drawn as a tag on your server. Draw it in a script: `` cs`<$Card />` ``. See [client components](/docs/thinking-in-backtick#client-components). ## From the compiler These are reported in the editor, and thrown when your server loads the file. ### `cs` was not compiled. Is @backtickjs set up for this project? Your server ran a script without the plugin that compiles them. Start it with `node --import @backtickjs/node-plugin`, or on Bun preload `@backtickjs/bun-plugin`. A new project's `npm start` already does. See [How it works](/docs/how-it-works#1-compiled-with-your-server). ### A `cs` client script is one expression or one block Statements need braces: `` cs`{ a(); b(); }` ``. See the [three shapes](/docs/scripts-in-depth#three-shapes). ### This `${…}` is in text, not code, so it isn't spliced A `${…}` inside a string or a comment in a script is text to the phone. As an element's child, write it in braces: `{${…}}`. ### A `cs` client script can't hold a template literal A script is a template literal itself, so `` \` `` can't start one inside it. Build the string with `+`: `n + "%"`, not `` `${n}%` ``. In a string or a comment, `` \` `` is a backtick, and fine. ### `$`-prefixed names are reserved for unbraced splices in a `cs` client script A script declared a name starting with `$`, as `const $label = …`. Those are splices; name it without the `$`. ### Can't splice `$name` unbraced: a `$`-prefixed host binding splices with braces A server variable whose own name starts with `$`, spliced as `$$name`. Write `${$name}`. ### A tag splices a host value by its name, e.g. `<$Card>`, not with `${…}` A tag was written as `<${Card}>`. Write `<$Card>`. ### `` is drawn by the client, so it belongs in a script A React Native tag was drawn on your server, outside a script. Draw it in one: `` cs`<$View>…` ``. ## From the bundler Thrown by `bundler.build`, for the screen it was building. ### Can't import `…` from "…": the client provides … A script uses a package missing from `packageVersions`. Add it there, at the version the app is built with, and to the app's modules. See [the three places a package goes](/docs/react-native-and-packages#any-package-your-app-ships). ### Can't import `…` from "…": it needs …, and the client provides … The app was built with a version of the package outside the range in `createImport`. Widen the range if the export works with that version, or serve that app a screen that doesn't use it. ### Can't splice the host function `…`: it's host code, and only runs on the host A function reached a splice, perhaps through `any`. Write the phone's code as a script, `` cs`(n: number) => …` ``. A server component is drawn with a tag in a braced splice: `{${}}`. ### Can't splice this `…` instance: only plain objects cross into a client script A class instance reached a splice. Cross its data as a plain object, `{ title: todo.title }`, or build it on the phone with a client function. ### Can't splice a symbol A symbol reached a splice, through `any`. Splice its key as a string, and make the symbol in a script: `` cs`Symbol.for($key)` ``. ### Can't splice a value that contains itself A value refers back to itself, such as a tree whose nodes point at their parents. Splice a copy without the back references. ### `…` is a client component, so it can't be a tag on the host A client component, `` cs`(props) => …` ``, was drawn as a tag on your server. Draw it in a script: `` cs`<$Card />` ``. ## From your app ### The bundle requires "…", which this app doesn't provide The bundle uses a package missing from the `modules` your app hands to `evaluate`. Add it, and install it in the app so its native code ships. If your server shouldn't have sent it, check its `packageVersions` for this app. See [the three places a package goes](/docs/react-native-and-packages#any-package-your-app-ships).