Fix some small runtime errors

server/rehype-hljs-var.ts

@@ -44,6 +44,7 @@ export const rehypeVarInHLJS = (
       // We only visit text nodes inside code snippets
       if (
         node.type !== "text" ||
+        !parent ||
         !parent.hasOwnProperty("tagName") ||
         (parent as Element).tagName !== "code"
       ) {
@@ -99,22 +100,25 @@ export const rehypeVarInHLJS = (
           continue;
         }
 
-        let hljsSpanValue;
+        let textValue;
         if ((el.children[i] as Element).tagName == "span") {
-          hljsSpanValue = (el.children[i].children[0] as Text).value;
+          textValue = (el.children[i].children[0] as Text).value;
         } else {
-          hljsSpanValue = el.children[i].value;
+          textValue = el.children[i].value;
+        }
+        if (!textValue) {
+          continue;
         }
 
         // This is an hljs span with only the placeholder as its child.
         // We don't need the span, so replace it with the original Var.
-        if (placeholdersToVars[hljsSpanValue]) {
-          el.children[i] = placeholdersToVars[hljsSpanValue];
+        if (placeholdersToVars[textValue]) {
+          el.children[i] = placeholdersToVars[textValue];
           continue;
         }
 
         const placeholders = Array.from(
-          hljsSpanValue.matchAll(new RegExp(placeholderPattern, "g"))
+          textValue.matchAll(new RegExp(placeholderPattern, "g"))
         );
 
         // No placeholders to recover, so there's nothing more to do.
@@ -138,23 +142,23 @@ export const rehypeVarInHLJS = (
         });
 
         let valueIdx = 0;
-        while (valueIdx < hljsSpanValue.length) {
+        while (valueIdx < textValue.length) {
           // The current index is in a placeholder, so add the original Var
           // component to newChildren.
           if (placeholderIndices.has(valueIdx)) {
             const placeholder = valueIdx + placeholderIndices.get(valueIdx);
             valueIdx += placeholder.length;
-            newChildren.push(placeholdersToVars[placeholderValue]);
+            newChildren.push(placeholdersToVars[placeholder]);
             continue;
           }
           // The current index is outside a placeholder, so assemble a text or
           // span node and push that to newChildren.
           let textVal = "";
           while (
             !placeholderIndices.has(valueIdx) &&
-            valueIdx < hljsSpanValue.length
+            valueIdx < textValue.length
           ) {
-            textVal += hljsSpanValue[valueIdx];
+            textVal += textValue[valueIdx];
             valueIdx++;
           }
           if (el.children[i].type == "text") {