diff --git a/io_export_psk_psa/helpers.py b/io_export_psk_psa/helpers.py
index 41f3c5b..34b74cb 100644
--- a/io_export_psk_psa/helpers.py
+++ b/io_export_psk_psa/helpers.py
@@ -9,11 +9,12 @@ def populate_bone_group_list(armature_object, bone_group_list):
     item.index = -1
     item.is_selected = True
 
-    for bone_group_index, bone_group in enumerate(armature_object.pose.bone_groups):
-        item = bone_group_list.add()
-        item.name = bone_group.name
-        item.index = bone_group_index
-        item.is_selected = True
+    if armature_object and armature_object.pose:
+        for bone_group_index, bone_group in enumerate(armature_object.pose.bone_groups):
+            item = bone_group_list.add()
+            item.name = bone_group.name
+            item.index = bone_group_index
+            item.is_selected = True
 
 
 def add_bone_groups_to_layout(layout):
diff --git a/io_export_psk_psa/psa/exporter.py b/io_export_psk_psa/psa/exporter.py
index bd10552..3754b47 100644
--- a/io_export_psk_psa/psa/exporter.py
+++ b/io_export_psk_psa/psa/exporter.py
@@ -71,7 +71,7 @@ def is_bone_filter_mode_item_available(context, identifier):
 class PsaExportOperator(Operator, ExportHelper):
     bl_idname = 'export.psa'
     bl_label = 'Export'
-    __doc__ = 'PSA Exporter (.psa)'
+    __doc__ = 'Export actions to PSA'
     filename_ext = '.psa'
     filter_glob: StringProperty(default='*.psa', options={'HIDDEN'})
     filepath: StringProperty(
@@ -174,7 +174,11 @@ class PsaExportOperator(Operator, ExportHelper):
         options.bone_filter_mode = property_group.bone_filter_mode
         options.bone_group_indices = [x.index for x in property_group.bone_group_list if x.is_selected]
         builder = PsaBuilder()
-        psa = builder.build(context, options)
+        try:
+            psa = builder.build(context, options)
+        except RuntimeError as e:
+            self.report({'ERROR_INVALID_CONTEXT'}, str(e))
+            return {'CANCELLED'}
         exporter = PsaExporter(psa)
         exporter.export(self.filepath)
         return {'FINISHED'}
@@ -204,6 +208,7 @@ class PSA_UL_ExportActionList(UIList):
 class PsaExportSelectAll(bpy.types.Operator):
     bl_idname = 'psa_export.actions_select_all'
     bl_label = 'Select All'
+    bl_description = 'Select all actions'
 
     @classmethod
     def poll(cls, context):
@@ -222,6 +227,7 @@ class PsaExportSelectAll(bpy.types.Operator):
 class PsaExportDeselectAll(bpy.types.Operator):
     bl_idname = 'psa_export.actions_deselect_all'
     bl_label = 'Deselect All'
+    bl_description = 'Deselect all actions'
 
     @classmethod
     def poll(cls, context):
diff --git a/io_export_psk_psa/psa/importer.py b/io_export_psk_psa/psa/importer.py
index 9d99131..620e24c 100644
--- a/io_export_psk_psa/psa/importer.py
+++ b/io_export_psk_psa/psa/importer.py
@@ -216,7 +216,7 @@ def on_armature_object_updated(property, context):
 
 
 class PsaImportPropertyGroup(bpy.types.PropertyGroup):
-    psa_file_path: StringProperty(default='', update=on_psa_file_path_updated)
+    psa_file_path: StringProperty(default='', update=on_psa_file_path_updated, name='PSA File Path')
     psa_bones: CollectionProperty(type=PsaImportPsaBoneItem)
     # armature_object: PointerProperty(name='Object', type=bpy.types.Object, update=on_armature_object_updated)
     action_list: CollectionProperty(type=PsaImportActionListItem)
@@ -260,6 +260,7 @@ class PSA_UL_ImportActionList(UIList):
 class PsaImportSelectAll(bpy.types.Operator):
     bl_idname = 'psa_import.actions_select_all'
     bl_label = 'All'
+    bl_description = 'Select all actions'
 
     @classmethod
     def poll(cls, context):
@@ -278,6 +279,7 @@ class PsaImportSelectAll(bpy.types.Operator):
 class PsaImportDeselectAll(bpy.types.Operator):
     bl_idname = 'psa_import.actions_deselect_all'
     bl_label = 'None'
+    bl_description = 'Deselect all actions'
 
     @classmethod
     def poll(cls, context):
@@ -335,11 +337,12 @@ class PSA_PT_ImportPanel(Panel):
 
 
 class PsaImportSelectFile(Operator):
-    bl_idname = "psa_import.select_file"
-    bl_label = "Select"
+    bl_idname = 'psa_import.select_file'
+    bl_label = 'Select'
     bl_options = {'REGISTER', 'UNDO'}
-    filepath: bpy.props.StringProperty(subtype="FILE_PATH")
-    filter_glob: bpy.props.StringProperty(default="*.psa", options={"HIDDEN"})
+    bl_description = 'Select a PSA file from which to import animations'
+    filepath: bpy.props.StringProperty(subtype='FILE_PATH')
+    filter_glob: bpy.props.StringProperty(default="*.psa", options={'HIDDEN'})
 
     def execute(self, context):
         context.scene.psa_import.psa_file_path = self.filepath
@@ -353,6 +356,7 @@ class PsaImportSelectFile(Operator):
 class PsaImportOperator(Operator):
     bl_idname = 'psa_import.import'
     bl_label = 'Import'
+    bl_description = 'Import the selected animations into the scene as actions'
 
     @classmethod
     def poll(cls, context):
diff --git a/io_export_psk_psa/psk/builder.py b/io_export_psk_psa/psk/builder.py
index f27bd12..c715f39 100644
--- a/io_export_psk_psa/psk/builder.py
+++ b/io_export_psk_psa/psk/builder.py
@@ -67,7 +67,8 @@ class PskBuilder(object):
         materials = OrderedDict()
 
         if armature_object is None:
-            # Static mesh (no armature)
+            # If the mesh has no armature object, simply assign it a dummy bone at the root to satisfy the requirement
+            # that a PSK file must have at least one bone.
             psk_bone = Psk.Bone()
             psk_bone.name = bytes('static', encoding='utf-8')
             psk_bone.flags = 0
@@ -79,13 +80,16 @@ class PskBuilder(object):
         else:
             bones = list(armature_object.data.bones)
 
-            # If bone groups are specified, get only the bones that are in the specified bone groups and their ancestors.
-            if len(options.bone_group_indices) > 0:
+            # If we are filtering by bone groups, get only the bones that are in the specified bone groups and their
+            # ancestors.
+            if options.bone_filter_mode == 'BONE_GROUPS':
                 bone_indices = get_export_bone_indices_for_bone_groups(armature_object, options.bone_group_indices)
                 bones = [bones[bone_index] for bone_index in bone_indices]
 
             # Ensure that the exported hierarchy has a single root bone.
             root_bones = [x for x in bones if x.parent is None]
+            print('root bones')
+            print(root_bones)
             if len(root_bones) > 1:
                 root_bone_names = [x.name for x in bones]
                 raise RuntimeError('Exported bone hierarchy must have a single root bone.'
diff --git a/io_export_psk_psa/psk/exporter.py b/io_export_psk_psa/psk/exporter.py
index 4e9b930..c9fdf90 100644
--- a/io_export_psk_psa/psk/exporter.py
+++ b/io_export_psk_psa/psk/exporter.py
@@ -64,7 +64,7 @@ def is_bone_filter_mode_item_available(context, identifier):
     input_objects = PskBuilder.get_input_objects(context)
     armature_object = input_objects.armature_object
     if identifier == 'BONE_GROUPS':
-        if not armature_object.pose or not armature_object.pose.bone_groups:
+        if not armature_object or not armature_object.pose or not armature_object.pose.bone_groups:
             return False
     # else if... you can set up other conditions if you add more options
     return True
@@ -73,7 +73,7 @@ def is_bone_filter_mode_item_available(context, identifier):
 class PskExportOperator(Operator, ExportHelper):
     bl_idname = 'export.psk'
     bl_label = 'Export'
-    __doc__ = 'PSK Exporter (.psk)'
+    __doc__ = 'Export mesh and armature to PSK'
     filename_ext = '.psk'
     filter_glob: StringProperty(default='*.psk', options={'HIDDEN'})
 
@@ -125,7 +125,11 @@ class PskExportOperator(Operator, ExportHelper):
         builder = PskBuilder()
         options = PskBuilderOptions()
         options.bone_group_indices = [x.index for x in property_group.bone_group_list if x.is_selected]
-        psk = builder.build(context, options)
+        try:
+            psk = builder.build(context, options)
+        except RuntimeError as e:
+            self.report({'ERROR_INVALID_CONTEXT'}, str(e))
+            return {'CANCELLED'}
         exporter = PskExporter(psk)
         exporter.export(self.filepath)
         return {'FINISHED'}
diff --git a/io_export_psk_psa/psk/importer.py b/io_export_psk_psa/psk/importer.py
index e651b0c..81283f8 100644
--- a/io_export_psk_psa/psk/importer.py
+++ b/io_export_psk_psa/psk/importer.py
@@ -167,7 +167,7 @@ class PskImporter(object):
 class PskImportOperator(Operator, ImportHelper):
     bl_idname = 'import.psk'
     bl_label = 'Export'
-    __doc__ = 'PSK Importer (.psk)'
+    __doc__ = 'Load a PSK file'
     filename_ext = '.psk'
     filter_glob: StringProperty(default='*.psk', options={'HIDDEN'})
     filepath: StringProperty(