fix window.onerror TypeError (#72)

diff --git a/CHANGES.md b/CHANGES.md
index c5fc0ac..9e452e5 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -5,6 +5,7 @@
 1. Support setting time interval to report segments.
 2. Fix segments report only send once
 3. Fix apache/skywalking#7335
+4. Fix apache/skywalking#7793
 
 ## 0.6.0
 
diff --git a/src/errors/js.ts b/src/errors/js.ts
index dd8a726..9ff7f49 100644
--- a/src/errors/js.ts
+++ b/src/errors/js.ts
@@ -33,7 +33,7 @@
         col,
         message,
         collector: options.collector,
-        stack: error.stack,
+        stack: error ? error.stack : '',
       };
       this.traceInfo();
     };