Importing PSD after renaming the root bone causes an error

[misaki-eymard]

Description:
After renaming the root bone, when you select Import into an existing skeleton and try to import a PSD, you will get the error:[error] Bone not found: root.

Expected behavior:
Since the root bone can be renamed, the PSD import should work even if the root bone is renamed.

Steps to reproduce:

1. Create a new project using Spine 4.2.36.
2. Rename the root bone to any name.
3. From the Spine menu, select Import PSD..., select any PSD file, and then select Import into an existing skeleton in the Import Data section.
4. When you press the Import button to run the import, an error pops up as shown below.
   
5. Press the Open Log button to check the log, and an error message [error] Bone not found: root should be logged.

The version of Spine in which this issue was found:
4.2.36

This issue was reported in the following thread on the forum:
https://esotericsoftware.com/forum/d/26792-importing-psd-after-renaming-the-root-bone-causes-an-error