diff --git a/src/index.ts b/src/index.ts
index d3c1786..2a15bb2 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -426,6 +426,7 @@ function getCallerFile() {
 }
 
 function getCallerFromExisting(err: Error): { file: string, line: number } {
+   if (!err || !err.stack) return { file: "NOFILE", line: 0 };
    let lines = err.stack.split("\n");
    let current = path.basename(__filename);
    lines.shift();// removing first line