Corrected the error handling for FFat.begin()

That function returns `true` on success.

Author: dhebbeker

lib/storage/storage.cpp

@@ -86,8 +86,8 @@ static void listFiles(const char *const dirname)
 static void switchToApplicationMode()
 {
     MSC.mediaPresent(false);
-    FFat.end();                    // invalidate cache
-    ESP_ERROR_CHECK(FFat.begin()); // update data
+    FFat.end();           // invalidate cache
+    assert(FFat.begin()); // update data
 }
 
 /**