diff --git a/server/scripts/modules/autocomplete.mjs b/server/scripts/modules/autocomplete.mjs
index 8a23f96..dd51176 100644
--- a/server/scripts/modules/autocomplete.mjs
+++ b/server/scripts/modules/autocomplete.mjs
@@ -297,7 +297,7 @@ class AutoComplete {
 	// if a click is detected on the page, generally we hide the suggestions, unless the click was within the autocomplete elements
 	checkOutsideClick(e) {
 		if (e.target.id === 'txtLocation') return;
-		if (e.target?.parentNode?.classList.contains(this.options.containerClass)) return;
+		if (e.target?.parentNode?.classList?.contains(this.options.containerClass)) return;
 		this.hideSuggestions();
 	}
 }
diff --git a/server/scripts/modules/utils/image.mjs b/server/scripts/modules/utils/image.mjs
index ac6c48a..d70271a 100644
--- a/server/scripts/modules/utils/image.mjs
+++ b/server/scripts/modules/utils/image.mjs
@@ -5,6 +5,11 @@ import { blob } from './fetch.mjs';
 // a list of cached icons is used to avoid hitting the cache multiple times
 const cachedImages = [];
 const preloadImg = (src) => {
+	if (!src || typeof src !== 'string') {
+		console.warn(`preloadImg expects a URL string, received: '${src}' (${typeof src})`);
+		return false;
+	}
+
 	if (cachedImages.includes(src)) return false;
 	blob(src);
 	cachedImages.push(src);
diff --git a/server/scripts/modules/utils/url-rewrite.mjs b/server/scripts/modules/utils/url-rewrite.mjs
index 1661add..08e4ad5 100644
--- a/server/scripts/modules/utils/url-rewrite.mjs
+++ b/server/scripts/modules/utils/url-rewrite.mjs
@@ -1,14 +1,23 @@
 // rewrite URLs to use local proxy server
 const rewriteUrl = (_url) => {
-	// Handle relative URLs - return them as-is since they don't need rewriting
+	if (!_url) {
+		throw new Error(`rewriteUrl called with invalid argument: '${_url}' (${typeof _url})`);
+	}
+
+	// Handle relative URLs early: return them as-is since they don't need rewriting
 	if (typeof _url === 'string' && !_url.startsWith('http')) {
 		return _url;
 	}
 
-	// Handle both string URLs and URL objects
-	const url = typeof _url === 'string' ? new URL(_url) : new URL(_url.toString());
+	if (typeof _url !== 'string' && !(_url instanceof URL)) {
+		throw new Error(`rewriteUrl expects a URL string or URL object, received: ${typeof _url}`);
+	}
+
+	// Convert to URL object (for URL objects, creates a copy to avoid mutating the original)
+	const url = new URL(_url);
 
 	if (!window.WS4KP_SERVER_AVAILABLE) {
+		// If running standalone in the browser, simply return a URL object without rewriting
 		return url;
 	}