Guardrail plugin restrict_to_topic crashes with PHP warnings and PluginNotFoundException when no provider is stored in config (#3577809) · Issues · project / ai

Guardrail plugin restrict_to_topic crashes with PHP warnings and PluginNotFoundException when no provider is stored in config

>>> [!note] Migrated issue   Reported by: [breidert](https://www.drupal.org/user/135619) Related to !1295 >>> [Tracker] Update Summary: [One-line status update for stakeholders] Short Description: [One-line issue summary for stakeholders] Check-in Date: MM/DD/YYYY Metadata is used by the <a href="https://www.drupalstarforge.ai/" title="AI Tracker">AI Tracker.</a> Docs and additional fields <a href="https://www.drupalstarforge.ai/ai-dashboard/docs" title="AI Issue Tracker Documentation">here</a>. [/Tracker] <h3 id="summary-problem-motivation">Problem/Motivation</h3> When a <code>restrict_to_topic guardrail</code> entity is imported via a Drupal recipe that intentionally omits <code>llm_provider</code>, <code>llm_model</code>, and <code>llm_config</code> from its YAML (the correct approach for provider-agnostic recipes), two separate failures occur. 1. PHP 8 warnings on the configuration form Opening the guardrail edit form produces: <ul> <li><code>Warning: Undefined array key "llm_ai_provider" in RestrictToTopic->buildConfigurationForm() (line 167)</code></li> <li><code>Warning: Undefined array key "llm_ajax_prefix" in RestrictToTopic->buildConfigurationForm() (line 170)</code></li> <li><code>Warning: Trying to access array offset on null in RestrictToTopic->buildConfigurationForm() (line 170)</code></li> <li><code>Warning: Undefined array key "llm_config" in RestrictToTopic->buildConfigurationForm() (line 174)</code></li> </ul> The form still renders and displays the site's default provider correctly. Saving it stores the provider and model, after which both warnings and the runtime error below disappear. 2. PluginNotFoundException at evaluation time Without saving the form first, evaluating the guardrail throws: <pre>Drupal\Component\Plugin\Exception\PluginNotFoundException: The "" plugin does not exist. Valid plugin IDs for Drupal\ai\AiProviderPluginManager are: openai</pre><code>processInput()</code> reads <code>$this->configuration['llm_provider']</code>, which is empty when the key is absent, and passes it directly to <code>createInstance()</code>. <h4 id="summary-steps-reproduce">Steps to reproduce</h4> <ol> <li>Install a recipe that imports a <code>restrict_to_topic</code> guardrail config file without <code>llm_provider</code>, <code>llm_mode</code>l, or <code>llm_config</code>, for example, the <a href="https://www.drupal.org/project/ai_recipe_guardrails_prompt_safety">AI Guardrails Prompt Safety recipe</a>.</li> <li>Navigate to <code>/admin/config/ai/guardrails</code> and open any of the installed guardrails (e.g. Liability: Legal Advice). → PHP 8 warnings appear.</li> <li>Without saving the form, assign the prompt_safety_liability guardrail set to an AI interaction and submit a prompt like "What medication should I take?" → PluginNotFoundException is thrown.</li> </ol> <h4>Expected behaviour</h4> <ul> <li>The form opens without warnings and pre-selects the site's configured default chat provider.</li> <li>Evaluating the guardrail uses the site's default chat provider when no provider is stored in the entity config.</li> <li>If no default chat provider is configured at all, the guardrail returns a clear <code>StopResult</code> with an actionable message rather than throwing an uncaught exception.</li> </ul> <h3 id="summary-proposed-resolution">Proposed resolution</h3> <code>buildConfigurationForm() </code>— add null-safe fallbacks: <pre>$form_state->setValue('llm_ai_provider',   $this->getConfiguration()['llm_provider']     ?? $this->getConfiguration()['llm_ai_provider']     ?? NULL ); $form_state->setValue('llm_ai_model',   $this->getConfiguration()['llm_model']     ?? ($this->getConfiguration()['llm_ajax_prefix']['llm_ai_model'] ?? NULL) ); $llm_configs = $this->getConfiguration()['llm_config'] ?? [];</pre><code>processInput()</code> — fall back to the site's default provider: <pre>$provider = $this->configuration['llm_provider'] ?? ''; $model    = $this->configuration['llm_model']    ?? ''; if (empty($provider)) {   $default = $this->getAiPluginManager()->getDefaultProviderForOperationType('chat');   if ($default === NULL) {     return new StopResult(       'No AI provider configured for topic classification. Please configure a default chat provider in the AI module settings.',       $this     );   }   $provider = $default['provider_id'];   $model    = $default['model_id']; } // ... $ai_provider->setConfiguration($this->configuration['llm_config'] ?? []);</pre><h3 id="summary-ai-usage">AI usage (if applicable)</h3> [x] AI Assisted Issue This issue was generated with AI assistance, but was reviewed and refined by the creator. [ ] AI Assisted Code This code was mainly generated by a human, with AI autocompleting or parts AI generated, but under full human supervision. [ ] AI Generated Code This code was mainly generated by an AI with human guidance, and reviewed, tested, and refined by a human. [ ] Vibe Coded This code was generated by an AI and has only been functionally tested. > Related issue: [Issue #3577506](https://www.drupal.org/node/3577506)

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