First transaction of a category doesn't work if it's split.

[dzaikos]

If the very first use of a category is within a split transaction, attempts to view all transactions in that category fail with this error:

Type error: Return value of FireflyIII\Repositories\Category\CategoryRepository::firstUseDate() must be an instance of Carbon\Carbon, string returned

[JC5]

Yes, this was discovered by somebody else as well, in a slightly different context. The next release will have a fix.