Sometimes, errors can appear in files generated when the project is compiled. These generated files typically include
.toc files. These files are used for things such as cross referencing, generating bibliographies, and making tables of contents.
If an error appears in one of these files, or if you would like to delete the files for some other reason, you do this by clearing the cache (a.k.a. "Recompile from scratch"). This is done by clicking into Logs and output files:
and scrolling down to the clear cached files button.
This will not delete anything you have written in your project, and the files will be generated again once you recompile.