Fix array offset notice on PHP 7.4 when installing extensions

[SharkyKZ]

Partial Pull Request for Issue #29414.

Summary of Changes

Fixes a notice on PHP 7.4 when uploading extension package fails.

Testing Instructions

1. Install an extension package with size over upload_max_filesize limit. Check PHP error log.
2. Try to install a random file, e.g. an image. Check Joomla's tmp directory.
3. Install an extension with size under upload_max_filesize limit.

Expected result

1. Installation aborted. No PHP notices.
2. Installation aborted and uploaded file is removed from tmp directory.
3. Extension installed successfully.

Actual result

1. Installation aborted. PHP notice: Trying to access array offset on value of type bool in administrator\components\com_installer\models\install.php on line 178

Documentation Changes Required

No.

[richard67]

@SharkyKZ For some reason I don't get the PHP notice of issue 1. with PHP 7.3. I get the correct red alert telling that maximum PHP file upload size is too small.

[SharkyKZ]

@richard67 The notice is not visible. You have to check PHP error log.

[richard67]

@SharkyKZ I always check PHP error log and have error reporting set to maximum in the backend. In my php.ini file I have E_ALL & ~E_DEPRECATED & ~E_STRICT, and I have log_errors = On; in my php.ini and a path to a log file set, which I watch permanently when testing and which shows me all. But the notice mentioned here I did not see.

[richard67]

@SharkyKZ Maybe it happens only with PHP 7.4?

[SharkyKZ]

@richard67 You're right. It's only on PHP 7.4+.

[richard67]

@SharkyKZ Then I can't test it, sorry :-(
Code review looks good though.

[mbabker]

Code change looks fine.

[laoneo]

I would remove here the \ to be consistent with the rest of the file.

[wilsonge]

Whilst consistency is definitely largely good for totally selfish reasons this will make my life easier merging to J4 😅 so merging as it is

[laoneo]

I have tested this item ✅ successfully on f850a21

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[viocassel]

I have tested this item ✅ successfully on f850a21

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/29416.}

[richard67]

RTC

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[wilsonge]

Thanks!