determineSolvability fails when no provider is set
>>> [!note] Migrated issue
<!-- Drupal.org comment -->
<!-- Migrated from issue #3552641. -->
Reported by: [unqunq](https://www.drupal.org/user/933228)
Related to !203
>>>
<p>While testing an agent via the drush command I noticed that when the default `Chat with Tools/Function Calling` option is not set the Bot response is </p>
<pre>Bot: The "" plugin does not exist. Valid plugin IDs for Drupal\ai\AiProviderPluginManager are: amazeeio, ollama</pre><p>The same agent called through an assistant seems to be working fine.</p>
<p>I suggest we add a check and print out a meaningful response to help the user understand what is going on.</p>
issue