🐛 Fix null element crash in get-attrs-from-styles

Guard against null element in get-attrs-from-styles so that when the
DOM node is not available the function returns the provided defaults
instead of throwing 'Cannot read properties of null (reading style)'.

Signed-off-by: Andrey Antukh <niwi@niwi.nz>

frontend/src/app/util/text/content/from_dom.cljs

@@ -38,21 +38,23 @@
 
 (defn get-attrs-from-styles
   [element attrs defaults]
-  (let [attrs (or attrs [])
-        value-empty? (fn [v]
-                       (or (nil? v)
-                           (and (string? v) (empty? v))
-                           (and (coll? v) (empty? v))))]
-    (reduce (fn [acc key]
-              (let [style (.-style element)
-                    value (if (contains? styles/mapping key)
-                            (let [style-name (styles/get-style-name-as-css-variable key)
-                                  [_ style-decode] (get styles/mapping key)]
-                              (style-decode (.getPropertyValue style style-name)))
-                            (let [style-name (styles/get-style-name key)]
-                              (styles/normalize-attr-value key (.getPropertyValue style style-name))))]
-                (assoc acc key (if (value-empty? value) (get defaults key) value))))
-            {} attrs)))
+  (if (nil? element)
+    (or defaults {})
+    (let [attrs (or attrs [])
+          value-empty? (fn [v]
+                         (or (nil? v)
+                             (and (string? v) (empty? v))
+                             (and (coll? v) (empty? v))))]
+      (reduce (fn [acc key]
+                (let [style (.-style element)
+                      value (if (contains? styles/mapping key)
+                              (let [style-name (styles/get-style-name-as-css-variable key)
+                                    [_ style-decode] (get styles/mapping key)]
+                                (style-decode (.getPropertyValue style style-name)))
+                              (let [style-name (styles/get-style-name key)]
+                                (styles/normalize-attr-value key (.getPropertyValue style style-name))))]
+                  (assoc acc key (if (value-empty? value) (get defaults key) value))))
+              {} attrs))))
 
 (defn get-text-span-styles
   [element]

frontend/test/frontend_tests/runner.cljs

@@ -21,6 +21,7 @@
    [frontend-tests.util-object-test]
    [frontend-tests.util-range-tree-test]
    [frontend-tests.util-simple-math-test]
+   [frontend-tests.util-text-from-dom-test]
    [frontend-tests.worker-snap-test]))
 
 (enable-console-print!)
@@ -52,5 +53,6 @@
    'frontend-tests.util-object-test
    'frontend-tests.util-range-tree-test
    'frontend-tests.util-simple-math-test
+   'frontend-tests.util-text-from-dom-test
    'frontend-tests.tokens.workspace-tokens-remap-test
    'frontend-tests.worker-snap-test))

frontend/test/frontend_tests/util_text_from_dom_test.cljs

@@ -0,0 +1,21 @@
+;; This Source Code Form is subject to the terms of the Mozilla Public
+;; License, v. 2.0. If a copy of the MPL was not distributed with this
+;; file, You can obtain one at http://mozilla.org/MPL/2.0/.
+;;
+;; Copyright (c) KALEIDOS INC
+
+(ns frontend-tests.util-text-from-dom-test
+  (:require
+   [app.common.types.text :as txt]
+   [app.util.text.content.from-dom :as fd]
+   [cljs.test :as t]))
+
+(t/deftest get-attrs-from-styles-with-null-element
+  (t/testing "returns defaults when element is nil"
+    (let [defaults txt/default-root-attrs
+          result   (fd/get-attrs-from-styles nil txt/root-attrs defaults)]
+      (t/is (= defaults result))))
+
+  (t/testing "returns empty map when element and defaults are both nil"
+    (let [result (fd/get-attrs-from-styles nil [] nil)]
+      (t/is (= {} result)))))