getgrav/grav · error · UnexpectedValueException

{% script in x %}: x is not a string

Error message

{% script in x %}: x is not a string

What it means

The {% script %} tag compiles the `in <expr>` clause (asset group) into $group = <expr> plus an is_string($group) check that throws UnexpectedValueException at render time on non-strings. The group selects where the script is output; it defaults to 'head' when the clause is missing.

Source

Thrown at system/src/Grav/Common/Twig/Node/TwigNodeScript.php:78

                ->subcompile($this->getNode('attributes'))
                ->raw(';' . PHP_EOL)
                ->write('if (!is_array($attributes)) {' . PHP_EOL)
                ->indent()
                ->write("throw new UnexpectedValueException('{% {$this->tagName} with x %}: x is not an array');" . PHP_EOL)
                ->outdent()
                ->write('}' . PHP_EOL);
        } else {
            $compiler->write('$attributes = [];' . PHP_EOL);
        }

        if ($this->hasNode('group')) {
            $compiler
                ->write('$group = ')
                ->subcompile($this->getNode('group'))
                ->raw(';' . PHP_EOL)
                ->write('if (!is_string($group)) {' . PHP_EOL)
                ->indent()
                ->write("throw new UnexpectedValueException('{% {$this->tagName} in x %}: x is not a string');" . PHP_EOL)
                ->outdent()
                ->write('}' . PHP_EOL);
        } else {
            $compiler->write('$group = \'head\';' . PHP_EOL);
        }

        if ($this->hasNode('priority')) {
            $compiler
                ->write('$priority = (int)(')
                ->subcompile($this->getNode('priority'))
                ->raw(');' . PHP_EOL);
        } else {
            $compiler->write('$priority = 10;' . PHP_EOL);
        }

        $compiler->write("\$assets = \\Grav\\Common\\Grav::instance()['assets'];" . PHP_EOL);
        $compiler->write("\$block = \$context['block'] ?? null;" . PHP_EOL);

View on GitHub (pinned to 6040efed04)

Solutions

1. Pass a plain string: {% script 'app.js' in 'bottom' %}
2. Default the expression: in group|default('bottom')
3. Initialize variables used as groups before the tag: {% set group = 'bottom' %}

Example fix

{% set group = null %}
{# before: null passed to in #}
{% script 'app.js' in group %}

{# after: string group name with default #}
{% script 'app.js' in group|default('bottom') %}

{# in Twig, guard the group variable before the tag #}
{% set group = group is defined and group is string ? group : 'head' %}
{% script 'app.js' in group %}

try { echo $twig->render($template, $data); } catch (UnexpectedValueException $e) { log_template_error($e); }

When it happens

Trigger: {% script 'app.js' in 2 %}; {% script 'app.js' in groups.bottom %} where groups is a nested array (element missing → null); passing a mapping or list as the group.

Common situations: Group variables never initialized; refactors that turn group names into arrays; index typos yielding null from an array lookup.

Related errors

• {% script with x %}: x is not an array
• {% link with x %}: x is not an array
• {% link in x %}: x is not a string
• {% {$this->tagName} with x %}: x is not an array
• {% {$this->tagName} in x %}: x is not a string

AI-assisted analysis of getgrav/grav@6040efed04 (2026-08-17). Data as JSON: /api/errors/f0b2ee664671b1a7. Report an issue: GitHub.