Drag and Drop of spectral library does not work (3.9RC1)

[Fabian Thiel]

Drag and drop of library from Data Sources does not work as expected, opens map + library window. Library Spectra are not shown.

Right click - Open in Spectral Library Viewer works.

An error has occurred while executing Python code: 

RuntimeError: wrapped C/C++ object of type LayerTreeNode has been deleted 
Traceback (most recent call last):
  File "C:\Users/thielf54/AppData/Roaming/QGIS/QGIS3\profiles\demo/python/plugins\enmapboxplugin\enmapbox\gui\dockmanager.py", line 358, in updateNodes
    self.profilesNode.addChildNode(n)
RuntimeError: wrapped C/C++ object of type LayerTreeNode has been deleted


Python version: 3.9.5 (tags/v3.9.5:0a7dcbd, May  3 2021, 17:27:52) [MSC v.1928 64 bit (AMD64)] 
QGIS version: 3.20.3-Odense Odense, 495fbaec 

‌

[Benjamin Jakimow]

please test if this erro still occurs. I resolved an issue related to mimedata handling and do not get any crashed drag and drop any more.