better error message

[jasverix]

Target branch: 4.x

• It is a Bug fix
• It is a New feature
• It is related to dependencies

Includes:

• Breaks BC
• Deprecations

The error message if a key fails is not very informational. The openssl extension provides more details, so we need that in the exception thrown.

[Spomky]

Hi,

Many thanks for this PR. Howvever it may send truncated messages or false.
An alternative could be as follows:

$opensslMessages = [];
while ($m = openssl_error_string()) {
    $opensslmessages[] = $m;
}
throw new InvalidArgumentException('Unable to load the key.', ['opensslMessages' => $opensslMessages]);

EDIT: to be rebased for 3.4.x