Fixes broken role owner ID splitting

We were attempting to split role owner identifiers even when the
value was `null`. This checks for the existence of the value prior
to attempting the split.

CHANGELOG.md

@@ -5,6 +5,7 @@
 ### Bug Fixes
 
 * Fixes bug where weapon nickname references in the HTML templates were broken.
+* Fixes bug where null value role owner references were having illegal operations performed on them.
 
 ## 0.3.0
 

module/helpers.js

@@ -120,8 +120,12 @@ Handlebars.registerHelper("doMath", function(...var_args) {
  */
 Handlebars.registerHelper("getEntity", function(type, id) {
   switch(type) {
-    case "actor": return game.actors.get(id.split("_")[1]);
-    default:      return null;
+    case "actor":
+      if (!id) return null;
+      return game.actors.get(id.split("_")[1]);
+
+    default:
+      return null;
   }
 });
 

module/vehicle.js

@@ -101,6 +101,8 @@ export function getPropulsion(propulsion) {
  * @return {Actor|null} The current Actor assigned to the role, if applicable.
  */
 export function getRoleOwner(assignment) {
+  if (!assignment) return null;
+
   const actorId = assignment.split("_")[1];
   const actor = game.actors.get(actorId);