**System Information**
Operating system: Darwin-17.7.0-x86_64-i386-64bit 64 Bits
Graphics card: AMD Radeon HD 6970M OpenGL Engine ATI Technologies Inc. 4.1 ATI-1.68.25
**Blender Version**
Broken: version: 2.91.0 Alpha, branch: master, commit date: 2020-09-17 21:51, hash: `rBcacd57b67a15`
Worked: (newest version of Blender that worked as expected)
**Short description of error**
Blender crash when you select Grid Display > 'Obstacle Levelset' or 'Outflow Levelset' in Fluid Simulation without 'Obstacles' or 'Outflow' objects in Scene.
**Exact steps for others to reproduce the error**
# Open a new default file.
# Select the Cube object in the scene
# Set it as a domain (in //Physics Properties// enable physics for //Fluid//, then set //Type// to //Domain//).
# Set //Domain Type// to //Liquid//
# Tick the //"Mesh"// checkbox in the //Liquid Properties > Fluid > Settings//.
# Tick //Is Resumeable// checkbox in the //Liquid Properties > Fluid > Settings > Cache// panel.
# Ensure that the cache type is set to //Replay// in //Liquid Properties > Fluid > Settings > Cache//.
# Add an object (e.g. sphere)
# In //Physics Properties// enable physics for //Fluid//, then set //Type// to //Flow//
# Set //Liquid Properties > Fluid > Settings > Flow Behavior// to //Inflow//.
# Play the simulation, then pause it after some frames
# In //Liquid Properties > Fluid > Viewport Display//, tick the checkbox for //Grid Display//
# Set //Liquid Properties > Fluid > Viewport Display > Grid Display > Field// to //Obstacle Levelset// or //Outflow Levelset//.
# Blender crashes immediately.
Keep in mind that there aren't 'Obstacles' or 'Outflow' objects in the scene.