"Load Mods from Save" blank page after failure and more

[knoxfighter]

After loading is finished the page will go blank with the error

Uncaught Error: Objects are not valid as a React child (found: object with keys {mods}). If you meant to render a collection of children, use an array instead.

When mods are not found (or the version is not available any more), the status will be error 500, therefore it will only partially complete, but it also successfully creates most of the mods.
Status code should not bee 500 in that case. Also it would be great to have a status page for what actually happened (list of mods that where installed or failed to install).