LanguageServers/FileDB: Allow m_project_root to be null

Author: https://github.com/itamar8910
Commit: 545b6af305
Pull-request: https://github.com/SerenityOS/serenity/pull/7095
Reviewed-by: https://github.com/awesomekling

Userland/DevTools/HackStudio/LanguageServers/FileDB.cpp

@@ -67,7 +67,8 @@ String FileDB::to_absolute_path(const String& filename) const
     if (LexicalPath { filename }.is_absolute()) {
         return filename;
     }
-    VERIFY(!m_project_root.is_null());
+    if (m_project_root.is_null())
+        return filename;
     return LexicalPath { String::formatted("{}/{}", m_project_root, filename) }.string();
 }