.buffer() returns error: "maxError for Buffer must be in the same units as the distance"

I would like to set a proj for .buffer(). When I set only a proj I am asked to set a non-zero maxError. When I set a maxError .buffer() returns: "Error in map(ID=0): Geometry.buffer: maxError for Buffer must be in the same units as the distance"

read-only link: https://code.earthengine.google.com/258401a214549d4209c2c23052ede684

Any ideas? Thank you!