Symfony version(s) affected: 3.4, 4.0

Description
Compiling a container while resolving environment variables fails if an environment variable is typecast to an array and isn't the last parameter defined.

When a value is resolved to an array in ContainerBuilder::resolveEnvPlaceholders and the foreach loop continues, stripos() throws a warning and returns null. Since the check is a strict comparison against false, null is considered a match, and since $placeholder !== $value, the logic falls through to the is_string() and is_numeric() checks, which fail, resulting in a RunTimeException.

How to reproduce

• Create two environment variables, at least one that will resolve to an array (json or const, csv in 4.1)
• Reference the environment variables as parameters and typehint appropriately (json, const)
  • Reference at least one environment variable after the array environment variable
• Compile the parameters, resolving the environment variables

Example code
https://github.com/jamesthomasonjr/symfony-di-array-bug

git clone git@github.com:jamesthomasonjr/symfony-di-array-bug.git
cd symfony-di-array-bug
composer install
bin/console.php

Possible Solution(s)

• Use break 2; to break out of the two for each loops in the cases where $placeholder === $value (would increase performance a little, too)
• Check that the value is a string at the beginning of the second for each loop, before calling stripos()