tasks: distinguish runtime crash vs task error in worker

src/taskworker.js

@@ -5,6 +5,7 @@
 const apptask = require('./apptask.js'),
     backupCleaner = require('./backupcleaner.js'),
     backuptask = require('./backuptask.js'),
+    BoxError = require('./boxerror.js'),
     dashboard = require('./dashboard.js'),
     database = require('./database.js'),
     dns = require('./dns.js'),
@@ -73,6 +74,15 @@ function exitSync(status) {
     process.exit(status.code);
 }
 
+function toTaskError(runError) {
+    if (runError instanceof BoxError) return runError.toPlainObject();
+    return {
+        message: `Task crashed. ${runError.message}`,
+        stack: runError.stack,
+        code: tasks.ECRASHED
+    };
+}
+
 // Main process starts here
 const startTime = new Date();
 
@@ -107,22 +117,18 @@ async function main() {
         await safe(tasks.update(taskId, progress), { debug });
     }
 
-    try {
-        debug(`Running task of type ${task.type}`);
-        const [runError, result] = await safe(TASKS[task.type.replace(/_.*/,'')].apply(null, task.args.concat(progressCallback)));
-        const progress = {
-            result: result || null,
-            error: runError ? JSON.parse(JSON.stringify(runError, Object.getOwnPropertyNames(runError))) : null,
-            percent: 100
-        };
+    debug(`Running task of type ${task.type}`);
+    const [runError, result] = await safe(TASKS[task.type.replace(/_.*/,'')].apply(null, task.args.concat(progressCallback)));
+    const progress = {
+        result: result || null,
+        error: runError ? toTaskError(runError) : null,
+        percent: 100
+    };
 
-        debug(`Task took ${(new Date() - startTime)/1000} seconds`);
+    debug(`Task took ${(new Date() - startTime)/1000} seconds`);
 
-        await safe(tasks.setCompleted(taskId, progress));
-        exitSync({ error: runError, code: 0 }); // code itself ran fine, but resulted in some error. so exit with success
-    } catch (error) {
-        exitSync({ error, code: 50 }); // do not call setCompleted() intentionally. the task code must be resilient enough to handle it
-    }
+    await safe(tasks.setCompleted(taskId, progress), { debug });
+    exitSync({ error: runError, code: runError instanceof BoxError ? 0 : 50 }); // handled error vs run time crash
 }
 
 main();