Fix "Trying to access array offset on null" warning

[xcopy]

Q	A
Is bugfix?	✔️
New feature?	❌
Breaks BC?	❌

Note: this does not solve the whole problem described in the issue #17365, but only part of it.

[codecov]

Codecov Report

Attention: Patch coverage is 18.75000% with 13 lines in your changes missing coverage. Please review.

Project coverage is 63.42%. Comparing base (49cfd3b) to head (52ff9db).
Report is 5 commits behind head on master.

Files with missing lines	Patch %	Lines
framework/caching/FileCache.php	25.00%	9 Missing ⚠️
framework/log/FileTarget.php	0.00%	4 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #20294      +/-   ##
============================================
- Coverage     64.84%   63.42%   -1.43%     
- Complexity    11412    11417       +5     
============================================
  Files           431      431              
  Lines         37147    37155       +8     
============================================
- Hits          24088    23565     -523     
- Misses        13059    13590     +531     

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[xcopy]

Btw, can find more similar code-block, i.e.

$error = error_get_last();
Yii::warning("...: {$error['message']}", __METHOD__);

and I guess the same kind of problem might arise with them.

However, I like the approach in the class yii\web\Session:

yii2/framework/web/Session.php

Lines 163 to 165 in 49cfd3b

	$error = error_get_last();
	$message = isset($error['message']) ? $error['message'] : 'Failed to start session.';
	Yii::error($message, __METHOD__);

[samdark]

👍 Would you please add a line for CHANGELOG? Thanks.

[xcopy]

Btw, can find more similar code-block, i.e.

$error = error_get_last();
Yii::warning("...: {$error['message']}", __METHOD__);

and I guess the same kind of problem might arise with them.

However, I like the approach in the class yii\web\Session:

yii2/framework/web/Session.php

Lines 163 to 165 in 49cfd3b

	$error = error_get_last();
	$message = isset($error['message']) ? $error['message'] : 'Failed to start session.';
	Yii::error($message, __METHOD__);

@samdark how about this one? Should fix 'em all?

[xcopy]

👍 Would you please add a line for CHANGELOG? Thanks.

Done ✅

[samdark]

Worth fixing all these if you're sure the issue could occur.

[bizley]

LGTM although I prefer classic ifs.

[xcopy]

@mtangoo I was thinking about it. Well, there is no standard: somewhere I can see throw new xxx(Yii::t(...)), somewhere just throw new xxx(...).

I can start a separate dedicated PR.

[xcopy]

LGTM although I prefer classic ifs.

Done ✅

[mtangoo]

I think we are good to go. @xcopy thanks for your time and effort. If you feel you can tackle another PR, feel free to do so!