Fix NaN when advancing through 0 search results

Author: jpenilla

web/src/routes/DiffSearch.svelte

@@ -16,6 +16,10 @@
 
     async function prevResult() {
         const files = await viewer.searchResults;
+        if (files.totalMatches === 0) {
+            currentMatchIdx = -1;
+            return;
+        }
         const startIdx = currentMatchIdx == -1 ? 0 : currentMatchIdx;
         currentMatchIdx = (startIdx - 1 + files.totalMatches) % files.totalMatches;
         viewer.activeSearchResult = files.getLocation(currentMatchIdx);
@@ -24,6 +28,10 @@
 
     async function nextResult() {
         const files = await viewer.searchResults;
+        if (files.totalMatches === 0) {
+            currentMatchIdx = -1;
+            return;
+        }
         currentMatchIdx = (currentMatchIdx + 1) % files.totalMatches;
         viewer.activeSearchResult = files.getLocation(currentMatchIdx);
         await scrollToMatch();