Now I see:

• Download Step 6 of hello World manual: https://github.com/scionescire/Joomla-3.2-Hello-World-Component/archive/step-6-using-the-database.zip
• Extract and remove all files in admin\sql\updates\mysql.
• zip the package and install it.

Red warning message but no other messages(!)

Warning : usort() expects parameter 1 to be array, string given in /libraries/src/Installer/Installer.php on line 1085
Warning : end() expects parameter 1 to be array, string given in /libraries/src/Installer/Installer.php on line 1098
{"success":true,"message":null,"messages":{"warning":["JFolder: :files: Path is not a folder. Path: \/administrator\/components\/com_helloworld\/sql\/updates\/mysql"],"message":["Installation of the component was successful."]},"data":{"redirect":"\/administrator\/index.php?option=com_installer&view=install"}}

The extension is installed now.

Reload the page: or navigate to another one:

• You see the "correct" message from the message queue that should be displayed before reload (immediately after installation):

Warning
JFolder: :files: Path is not a folder. Path: /administrator/components/com_helloworld/sql/updates/mysql

Pro: Thus it's somehow an issue from my point of view even if the extension package manifest is misconfigured because the redirect/page reload is suppressed.

Their should be at least an additional message for users that the extension has been installed.

Irritating.

Contra: On the other hand I would say it's the job of the developer to avoid such errors before releasing an extension and a developer should be able to understand the red message. Not a Joomla core issue.

Contra would rule for me and I would close the issue.

After installation

After page reload

If nothing else, a more informative exception ( or performing some validation on the component xml file ) would make the problem a lot easier to troubleshoot- figuring out how to construct a component is pretty tricky even as an experienced developer and supporting people in doing that is probably a positive for the Joomla ecosystem.

@glenatron it woild be appreciated if you write a pr that make the install process smoother or bring us better error handling

This issue here could be related to an issue which the patchtester component had, see comment here: joomla-extensions/patchtester#186 (comment).

@HLeithner sure, is the best way to raise the message to use application->enqueueMessage($msg, 'error'); or is something else more correct in this circumstance?

Can confirm that failing to run the SQL installer file was me messing up the markup of my config file, so that is not relevant to this message at all.

@infograf768 can the Issue be closed?

@glenatron enqueue a message would be enough so if the developer test his component at least once he should see the problem.

I'm closing this. You can reference this issue in your PR.

Maybe you're right and I don't understand your thoughts but there is already a correct message in the queue as you can see in the red error:

{"success":true,"message":null,"messages":{"warning":["JFolder: :files: Path is not a folder. Path: /administrator/components/com_helloworld/sql/updates/mysql"],"message":["Installation of the component was successful."]},"data":{"redirect":"/administrator/index.php?option=com_installer&view=install"}}

but it's not displayed. From my point of view the whole routine should stop if $files is not an array because the whole following db query is broken then.

https://github.com/joomla/joomla-cms/blob/staging/libraries/src/Installer/Installer.php#L1098

2 possible ways, stop the installation or let the installer ignore the missing sql file.

Because I prefer to learn coding "the hard way" I would leave it as ist is. See my "Contra" in #25202 (comment)
Why should Joomla react friendly here? The extension is wrongly configured. The red message contains all necessary informations for developers and more helpful informations than the message queue can provide.