handle non-document situations w/behaviors

Author: 1cg

src/core/runtime/runtime.js

@@ -374,7 +374,7 @@ export class Runtime {
 
         assignToNamespace(elt, nameSpace, name, value) {
             let root
-            if (typeof document !== "undefined" && elt === document.body) {
+            if (elt == null || (typeof document !== "undefined" && elt === document.body)) {
                 root = this.#globalScope;
             } else {
                 root = this.getHyperscriptFeatures(elt);

src/parsetree/features/behavior.js

@@ -27,7 +27,7 @@ export class BehaviorFeature extends Feature {
         const hs = this.hs;
 
         runtime.assignToNamespace(
-            runtime.globalScope.document && runtime.globalScope.document.body,
+            null,
             nameSpace,
             name,
             function (target, source, innerArgs) {