This report was generated with PropEr's master branch on 24/8/2020 commit.
PropEr shrinks this example to
{d,0,{d,0,1}}(most of the time){d,0,{d,0,-1}}(often) but also to{d,0,{d,0,{d,0,-1}}}{a,0,{d,0,{d,0,1}}}{d,0,{a,0,0}}{d,0,{a,-1,1}}{d,0,{a,1,-1}}{d,0,{a,5,-5}}{d,0,{a,-6,6}}{d,0,{a,3,-3}}
where the a tag means addition and d division.
Over 100 runs, PropEr found a counterexample after 7 to 43 tests, and performed between 1 and 9 shrinking attempts.
See the report of the run for more information.