Exception: error, no selected mesh objects

Hi guys, I got this trying to export my scene in blender 2.81 (first time I tried the tool). It exported a bunch of images, but for some reason the mesh part fails it seems.

```
Traceback (most recent call last):
File "/home/james/.config/blender/2.81/scripts/addons/babylon_js/__init__.py", line 65, in execute
exporter.execute(context, self.filepath)
File "/home/james/.config/blender/2.81/scripts/addons/babylon_js/json_exporter.py", line 111, in execute
mesh = Mesh(object, scene, self)
File "/home/james/.config/blender/2.81/scripts/addons/babylon_js/mesh.py", line 146, in __init__
recipe = BakingRecipe(bpyMesh, exporter)
File "/home/james/.config/blender/2.81/scripts/addons/babylon_js/materials/baking_recipe.py", line 105, in __init__
self.bakedMaterial.bake(bpyMesh, self)
File "/home/james/.config/blender/2.81/scripts/addons/babylon_js/materials/material.py", line 138, in bake
bpy.ops.uv.smart_project(angle_limit = 66.0, island_margin = 0.0, user_area_weight = 1.0, use_aspect = True, stretch_to_bounds = True)
File "/home/james/Downloads/blender-2.81-linux-glibc217-x86_64/2.81/scripts/modules/bpy/ops.py", line 201, in __call__
ret = op_call(self.idname_py(), None, kw)
RuntimeError: Error: Traceback (most recent call last):
File "/home/james/Downloads/blender-2.81-linux-glibc217-x86_64/2.81/scripts/startup/bl_operators/uvcalc_smart_project.py", line 1032, in execute
self.stretch_to_bounds,
File "/home/james/Downloads/blender-2.81-linux-glibc217-x86_64/2.81/scripts/startup/bl_operators/uvcalc_smart_project.py", line 744, in main
raise Exception("error, no selected mesh objects")
Exception: error, no selected mesh objects

location: /home/james/Downloads/blender-2.81-linux-glibc217-x86_64/2.81/scripts/modules/bpy/ops.py:201

location: :-1

```

I noticed there were no export settings. It said something about finding the settings in the properties panel

Reproduce the export in Blender 2.81, then trace the call from json_exporter.py through mesh.py, materials/baking_recipe.py, and materials/material.py to bpy.ops.uv.smart_project. Compare the exporter context with Blender's UV operator requirements; done means mesh export completes without the reported no-selected-mesh-objects exception while the scene's images still export.

Written by the indexing model from the issue text.