The search function in the K2 Tools module is buggy as it is presuming that the site has Joom!Fish installed.

Reproducing the problem:

1. Install Joomla!

2. Install K2.

3. Don't install Joom!Fish.

4. Add one article in K2.

5. Enable the K2 tools module.

6. Enable Debugging in the Joomla! configuration.

7. Perform a search about any word which is in the article.

You will see a lot of issues coming.

 

This bug is basically because the search module always performs (tries) search in the Joom!Fish content tables, even if Joom!Fish is not installed.

Temporary "workaround" - install and uninstall Joom!Fish. However this is not very smart solution.

I confirm this behavior in 2.4.1 and the current 2.5 SVN.