fix: handle cases when properties undefined in replaceSymbols (#62)

Author: evilebottnawi

.travis.yml

@@ -17,15 +17,15 @@ cache:
 
 matrix:
   include:
-    - node_js: "11"
+    - node_js: "12"
       env: JOB_PART=pretest
     - node_js: "6"
       env: JOB_PART=test
     - node_js: "8"
       env: JOB_PART=test
     - node_js: "10"
       env: JOB_PART=test
-    - node_js: "11"
+    - node_js: "12"
       env: JOB_PART=test
 
 before_script:

src/replaceSymbols.js

@@ -2,12 +2,13 @@ import replaceValueSymbols from "./replaceValueSymbols.js";
 
 const replaceSymbols = (css, replacements) => {
   css.walk(node => {
-    if (node.type === "decl") {
+    if (node.type === "decl" && node.value) {
       node.value = replaceValueSymbols(node.value, replacements);
-    } else if (node.type === "rule") {
+    } else if (node.type === "rule" && node.selector) {
       node.selector = replaceValueSymbols(node.selector, replacements);
     } else if (
       node.type === "atrule" &&
+      node.params &&
       ["media", "supports"].includes(node.name.toLowerCase())
     ) {
       node.params = replaceValueSymbols(node.params, replacements);