Merge branch '6.x' into 7.x

# Conflicts:
#	README.md

Translator.php

@@ -122,7 +122,7 @@ public function get($key, array $replace = [], $locale = null, $fallback = true)
             $locales = $fallback ? $this->localeArray($locale) : [$locale];
 
             foreach ($locales as $locale) {
-                if (! is_null($line = $this->getLine(
+                if (! empty($line = $this->getLine(
                     $namespace, $group, $locale, $item, $replace
                 ))) {
                     return $line ?? $key;