PHP Fatal error: Uncaught InvalidArgumentException: item should be a Collection or an array or an object

Overview of the issue

You may see the following error after updating to WPML String Translation 3.1.2:

[17-Sep-2020 10:51:21 UTC] PHP Fatal error:  Uncaught InvalidArgumentException: item should be a Collection or an array or an object in .../wp-content/plugins/sitepress-multilingual-cms/vendor/wpml/fp/core/Obj.php:94
Stack trace:
#0 [internal function]: WPML\FP\Obj::WPML\FP{closure}(NULL, 'attachment_id', false)
#1 .../wp-content/plugins/sitepress-multilingual-cms/vendor/wpml/fp/core/functions.php(141): call_user_func_array(Object(Closure), Array)
#2 [internal function]: WPML\FP\Obj::WPML\FP{closure}(NULL, 'attachment_id', false)
#3 .../wp-content/plugins/sitepress-multilingual-cms/vendor/wpml/collect/src/Illuminate/Support/Traits/Macroable.php(56): call_user_func_array(Object(Closure), Array)
#4 .../wp-content/plugins/sitepress-multilingual-cms/vendor/wpml/fp/core/Obj.php(78): WPML\FP\Obj::__callStatic('propOr', Array)
#5 [internal function]: WPML\FP\Obj::WPML\FP{closure}('attachment_id', false)
#6 .../wp-content/plugins/sitepress-multilingual-cms/vendor/wpml/f in /home/add/public_html/wp-content/plugins/sitepress-multilingual-cms/vendor/wpml/fp/core/Obj.php on line 94

Workaround

• Make a full backup of your site.
• Open your wpml-string-translation/inc/admin-texts/wpml-admin-texts.class.php file.
• Look for the line 255
• Replace:

  	private function isAdminText( $key, $name ) {
  		return null !== Wrapper::of( $this->getSubKey( $key, $name ) )
  		                       ->map( [ self::class, 'getKeysParts' ] )
  		                       ->map( invoke( 'reduce' )->with( flip( Obj::prop() ), $this->getOptionNames() ) )
  		                       ->get();
  	}
  

• With:

  	private function isAdminText($key, $name) {
  		try {
  			return null !== Wrapper::of($this->getSubKey($key, $name))
  					->map([self::class, 'getKeysParts'])
  					->map(invoke('reduce')->with(flip(Obj::prop()), $this->getOptionNames()))
  					->get();
  		} catch (Exception $ex) {
  			error_log($ex->getMessage() . ' Option Key ' . $key);
  		}
  	}