Armature object in Blender is exported as a Skeleton node along with rest position (transform in Godot) of bones.
The three check boxes
Local Location (colored in red) must be ticked when building
armature in Blender, so that the exported bone transform be
consistent between Blender and Godot
Blender put rigged mesh vertices which has no bone weights at its original position, but these vertices would be placed at (0, 0, 0) in Godot, making the mesh deformed. Therefore, the exporter would raise an error for any vertex with no bone weights detected in a rigged mesh.
Note that the non-deform bone can be configured as not exported
by enabling the
Exclude Control Bones; the deform bone
checkbox is shown in the picture.
A bone can be the parent of an object in Blender; this relation is exported as a BoneAttachment node in the Godot scene.