Handle variables in binary ops in function calls

src/args.rs

@@ -143,7 +143,8 @@ pub(crate) fn eat_call_args<I: Iterator<Item = Token>>(
             TokenKind::Variable(_) => {
                 let v = toks.next().unwrap();
                 devour_whitespace_or_comment(toks);
-                if toks.next().unwrap().is_symbol(Symbol::Colon) {
+                if toks.peek().unwrap().is_symbol(Symbol::Colon) {
+                    toks.next();
                     name = v.kind.to_string();
                 } else {
                     val.push(v);

tests/functions.rs

@@ -48,3 +48,8 @@ test!(
     "@function a() {\n  @return 1; @return 2;\n}\n\nb {\ncolor: a();\n}\n",
     "b {\n  color: 1;\n}\n"
 );
+test!(
+    value_after_variable,
+    "$x: 0;\na {\n  color: if($x != 0, a, b);\n}\n",
+    "a {\n  color: b;\n}\n"
+);