Spent almost an hour trying to fix non-existent issue. It's was silly of me, but vips was keeping to throw "Unable to find library" exception and it's confusing. In the end issue was with ffi.enabled=off, of course :(
(In my defense: debugging on a remote server with a different OS isn't so easy, and its php-fpm, and the project's exception handler clears stdout and I only see exceptions from vips in the project log)

Wanted to make a small PR, but not sure how to fix this better. One idea so far - to simple check for string ffi.enable in exception message (https://github.com/libvips/php-vips/blob/master/src/FFI.php#L252):

 $lastException = null; 
 foreach ($libraryPaths as $path) {
    try {
        ...
    } catch (\FFI\Exception $e) {
        $lastException = $e;
        Utils::debugLog("init", ["msg" => "library load failed", "exception" => $e]);
    }
}

 if ($vips === null) {
    if ($lastException && strpos($lastException->getMessage(), "ffi.enable") !== false) {
        throw new Exception("Please, check your FFI configuration", 0, $lastException);
    }
    ...
 }

Or may be without message and just re-throw $lastException?