diff --git a/src/tasks.js b/src/tasks.js
index f81fa2fcc..0c7de65b9 100644
--- a/src/tasks.js
+++ b/src/tasks.js
@@ -178,7 +178,7 @@ function startTask(id, options, callback) {
 
         const [getError, task] = await safe(get(id));
 
-        let taskError;
+        let taskError = null;
         if (!getError && task.percent !== 100) { // taskworker crashed or was killed by us
             if (code === 0) {
                 taskError = {
@@ -204,7 +204,7 @@ function startTask(id, options, callback) {
 
         if (callback) callback(taskError, task ? task.result : null);
 
-        debug(`startTask: ${id} done. error: `, taskError);
+        debug(`startTask: ${id} done. error: ${taskError}`);
     });
 
     if (options.timeout) {