diff --git a/src/pyj/book_list/main.pyj b/src/pyj/book_list/main.pyj
index e7b47ba5d7..bcae29c64d 100644
--- a/src/pyj/book_list/main.pyj
+++ b/src/pyj/book_list/main.pyj
@@ -33,14 +33,19 @@ def remove_initial_progress_bar():
         p.parentNode.removeChild(p)
 
 def onerror(msg, script_url, line_number, column_number, error_object):
-    if error_object:
-        console.log(error_object)
+    if error_object is None:
+        # This happens for cross-domain errors (probably javascript injected
+        # into the browser via extensions/ userscripts and the like). It also
+        # happens all the time when using Chrom on Safari, so ignore this
+        # type of error
+        console.log(f'Unhandled error from external javascript, ignoring: {msg} {script_url} {line_number}')
+        return
+    console.log(error_object)
     try:
         fname = script_url.rpartition('/')[-1] or script_url
         msg = msg + '<br><span style="font-size:smaller">' + 'Error at {}:{}:{}'.format(fname, line_number, column_number or '') + '</span>'
         details = ''
-        if error_object:
-            details = traceback.format_exception(error_object).join('')
+        details = traceback.format_exception(error_object).join('')
         error_dialog(_('Unhandled error'), msg, details)
         return True
     except:
diff --git a/src/pyj/read_book/iframe.pyj b/src/pyj/read_book/iframe.pyj
index 55f0cdce4a..37476b107d 100644
--- a/src/pyj/read_book/iframe.pyj
+++ b/src/pyj/read_book/iframe.pyj
@@ -138,8 +138,14 @@ class IframeBoss:
         self.send_message('print', string=' '.join(map(str, args)))
 
     def onerror(self, msg, script_url, line_number, column_number, error_object):
-        if error_object:
-            console.log(error_object)
+        if error_object is None:
+            # This happens for cross-domain errors (probably javascript injected
+            # into the browser via extensions/ userscripts and the like). It also
+            # happens all the time when using Chrom on Safari, so ignore this
+            # type of error
+            console.log(f'Unhandled error from external javascript, ignoring: {msg} {script_url} {line_number}')
+            return
+        console.log(error_object)
         try:
             fname = script_url.rpartition('/')[-1] or script_url
             msg = msg + '<br><span style="font-size:smaller">' + 'Error at {}:{}:{}'.format(fname, line_number, column_number or '') + '</span>'