Error: Class "DocumentCreateManagerController" not found when enable_template_picker_in_tree is off #16004

Bug report

Summary

When the template picker in 3.0.0-rc1 is DISABLED, or when using Collections or a quick dashboard link to create a new document, an error is thrown.

Step to reproduce

Try to navigate to the resource/create controller with a pre-defined class key, e.g.:

• https://localhost/3.x/manager/?a=resource/create&class_key=MODX\Revolution\modDocument&parent=1&context_key=web

URLs like this are generated with the template picker off and right clicking in the tree > create document here, or through Collections or Quickstart Buttons.

Observed behavior

Error: Class "DocumentCreateManagerController" not found

Errors:

    ResourceManagerController::getInstance()
    MODX\Revolution\modManagerResponse->outputContent()
    MODX\Revolution\modManagerRequest->prepareResponse()
    MODX\Revolution\modManagerRequest->handleRequest()

What's interesting though: it does work for weblinks, static resources and symlinks. So it seems to be document-specific.

When removing the class_key URL parameter, it also works fine.

Expected behavior

Allow creating a new document without the template picker.

Related issue(s)/PR(s)

N/a

Environment

3.0.0-rc1