Module not found: Error: Can't resolve the relative path .d.ts file

So my issue is that I have a problem with an import of .d.ts file with exported declare types. I tried to use the .d.ts (unnecesary though), changing a path etc. The file contents are moved from another path that is imported via a '@project_name/core'. However I am not getting any other errors regarding it, just the Module not found.