[FIX] error cause

src/print.js

@@ -130,7 +130,10 @@ const doPrint = (socket, request) => {
             socket.emit(SHOW_PRINT_STATUS, {
                 status: 'error',
                 printer: request.printer,
-                cause: e
+                cause: {
+                    id: 'conversion_error',
+                    error: e
+                }
             })
 
             return
@@ -165,7 +168,10 @@ const doPrint = (socket, request) => {
             socket.emit(SHOW_PRINT_STATUS, {
                 status: 'error',
                 printer: request.printer,
-                cause: e
+                cause: {
+                    id: 'print_error',
+                    error: e
+                }
             })
         }
     })