If your server has a support page, you should report any bugs/issues you encounter there first.
Reporting to your support page before reporting to the developers makes their job easier, as they don't have to deal with bug reports that might not have anything to do with them.
Try to provide as much information as you can about the bug, including the **full** text of any error messages or notices, and any steps required to replicate the problem in as much detail as possible.
It's generally better to provide too much information than not enough.