diff --git a/builder/index.html b/builder/index.html
index 1a14ed3..6385eb9 100644
--- a/builder/index.html
+++ b/builder/index.html
@@ -406,6 +406,8 @@
                             </div>
                             <div class="col text-center">
                                 <div id="summary-box"></div>
+                                <div id="err-box"></div>
+                                <div id="stack-box"></div>
                                 <div id="str-warnings"></div>
                                 <div id="dex-warnings"></div>
                                 <div id="int-warnings"></div>
diff --git a/js/builder.js b/js/builder.js
index 3b6cf33..78e4a99 100644
--- a/js/builder.js
+++ b/js/builder.js
@@ -443,6 +443,11 @@ function init() {
     builder_graph_init();
 }
 
+window.onerror = function(message, source, lineno, colno, error) {
+    document.getElementById('err-box').textContent = message;
+    document.getElementById('stack-box').textContent = error.stack;
+};
+
 (async function() {
     let load_promises = [ load_init(), load_ing_init(), load_tome_init() ];
     await Promise.all(load_promises);