vim-patch:9.0.0804: crash when trying to divide a number by -1

Problem:    Crash when trying to divice the largest negative number by -1.
Solution:   Handle this case specifically.
cdef1cefa2

src/nvim/eval.c

@@ -330,6 +330,10 @@ varnumber_T num_divide(varnumber_T n1, varnumber_T n2)
     } else {
       result = VARNUMBER_MAX;
     }
+  } else if (n1 == VARNUMBER_MIN && n2 == -1) {
+    // specific case: trying to do VARNUMBAR_MIN / -1 results in a positive
+    // number that doesn't fit in varnumber_T and causes an FPE
+    result = VARNUMBER_MAX;
   } else {
     result = n1 / n2;
   }

src/nvim/testdir/test_expr.vim

@@ -602,6 +602,12 @@ func Test_eval_after_if()
   call assert_equal('b', s:val)
 endfunc
 
+func Test_divide_by_zero()
+  " only tests that this doesn't crash, the result is not important
+  echo 0 / 0
+  echo 0 / 0 / -1
+endfunc
+
 " Test for command-line completion of expressions
 func Test_expr_completion()
   CheckFeature cmdline_compl