fix(file_cache): if write failure, produce log record instead of exception (#4352)

caches/FileCache.php

@@ -54,10 +54,13 @@ class FileCache implements CacheInterface
         ];
         $cacheFile = $this->createCacheFile($key);
         $bytes = file_put_contents($cacheFile, serialize($item));
-        // todo: Consider tightening the permissions of the created file. It usually allow others to read, depending on umask
+
+        // TODO: Consider tightening the permissions of the created file.
+        // It usually allow others to read, depending on umask
+
         if ($bytes === false) {
-            // Consider just logging the error here
-            throw new \Exception(sprintf('Failed to write to: %s', $cacheFile));
+            // Typically means no disk space remaining
+            $this->logger->warning(sprintf('Failed to write to: %s', $cacheFile));
         }
     }