Fix print history bug (#324)

Author: luksan47

app/Console/Commands.php

@@ -20,7 +20,8 @@ public static function updateCompletedPrintingJobs()
         if (self::isDebugMode()) {
             $result = [0];
         } else {
-            $result = exec("lpstat -W completed -o " . config('print.printer_name') . " | awk '{print $1}'", $result);
+            $result = [];
+            exec("lpstat -W completed -o " . config('print.printer_name') . " | awk '{print $1}'", $result);
         }
         return $result;
     }

app/Http/Controllers/PrintController.php

@@ -218,9 +218,13 @@ public function cancelPrintJob($id) {
     /** Private helper functions */
 
     private function updateCompletedPrintingJobs() {
-        $result = Commands::updateCompletedPrintingJobs();
-        Log::info("Completed jobs: " . implode(', ', $result));
-        PrintJob::whereIn('job_id', $result)->update(['state' => PrintJob::SUCCESS]);
+        try {
+            $result = Commands::updateCompletedPrintingJobs();
+            Log::info("Completed jobs: " . implode(', ', $result));
+            PrintJob::whereIn('job_id', $result)->update(['state' => PrintJob::SUCCESS]);
+        } catch (\Exception $e) {
+            Log::error("Printing error at line: " . __FILE__ . ":" . __LINE__ . " (in function " . __FUNCTION__ . "). " . $e->getMessage());
+        }
     }
 
     private function storeFile($file)