Fix #122.

Refuse to divide a color by zero.

src/value/operator.rs

@@ -1,5 +1,6 @@
 use crate::css::{CssString, Value};
 use crate::value::{ListSeparator, Numeric, Quotes};
+use num_traits::Zero;
 use std::fmt;
 
 /// An operator that can be used in a sass value.
@@ -140,10 +141,10 @@ impl Operator {
             Operator::Div if a.is_calculated() || b.is_calculated() => {
                 match (a, b) {
                     (Value::Color(a, _), Value::Numeric(b, _))
-                        if b.is_no_unit() =>
+                        if b.is_no_unit() && !b.value.is_zero() =>
                     {
-                        let bn = b.as_ratio().ok()?;
-                        Some((a.to_rgba().as_ref() / bn).into())
+                        let bn = dbg!(b).as_ratio().ok()?;
+                        Some((dbg!(a).to_rgba().as_ref() / bn).into())
                     }
                     (Value::Numeric(ref a, _), Value::Numeric(ref b, _)) => {
                         Some((a / b).into())

tests/basic_manual.rs

@@ -384,6 +384,25 @@ fn issue_116() {
     );
 }
 
+/// https://github.com/kaj/rsass/issues/122
+/// A division by zero that causes a panic
+mod issue_122 {
+    use super::check_value;
+    // Note: The important thing here is not to panic, the exact
+    // output may be changed in the future, maybe to report an error.
+    #[test]
+    fn reduced() {
+        check_value("(#111 + #aaa)/0", "#bbbbbb/0")
+    }
+    #[test]
+    fn reported() {
+        check_value(
+            "54A444/0+-4444M4#444/-4444/0+-4444M4#444+44/0+444/0+.44444O#444+44/0+4/46",
+            "InfinityA444-4444M4 black/0-4444M4 #444InfinityInfinity0.44444O #444Infinity0.0869565217",
+        )
+    }
+}
+
 /// Test auto-converted from "sass-spec/spec/libsass/rel.hrx", except one failing unit calculation.
 #[test]
 fn rel() {