fix: safely disconnect themeChangeObserver with optional chaining

[flang]

Close #20

Summary by CodeRabbit

• Bug Fixes
  • Prevented rare runtime errors in the Markdown editor by making the theme observer cleanup more robust, improving stability during theme changes and when the editor is removed.

[coderabbitai]

Walkthrough

Replaces a direct property access in unobserveThemeChange with optional chaining to safely check for themeChangeObserver on markDownEditor.$connector before disconnecting and clearing it.

Changes

Cohort / File(s)	Change Summary
Frontend connector null-guard src/main/resources/META-INF/resources/frontend/fcMarkdownEditorConnector.js	Updated condition to use optional chaining (markDownEditor?.$connector?.themeChangeObserver) to avoid runtime errors when markDownEditor or $connector is undefined; logic for disconnecting and clearing observer unchanged.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

Assessment against linked issues

Objective	Addressed	Explanation
Prevent null/undefined access of $connector in unobserveThemeChange to avoid console error [#20]	✅

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[coderabbitai]

Actionable comments posted: 0

🔭 Outside diff range comments (2)

src/main/resources/META-INF/resources/frontend/fcMarkdownEditorConnector.js (2)

24-31: Prevent re-initialization lockout after unobserve

observeThemeChange returns early if $connector exists, but unobserveThemeChange does not remove $connector, only nulls themeChangeObserver. On a re-attach for the same element instance, observeThemeChange will bail out and never recreate the observer. This silently disables theme observation after the first detach/attach cycle.

Refactor the guard to only skip when an active observer exists, and ensure $connector is initialized when missing.

Apply this diff:

-      // Check whether the connector was already initialized for markDownEditor
-      if (markDownEditor.$connector) {
-        return;
-      }
-
-      markDownEditor.$connector = {};
+      // Initialize connector namespace if missing
+      if (!markDownEditor.$connector) {
+        markDownEditor.$connector = {};
+      }
+      // Skip only if an observer is already active
+      if (markDownEditor.$connector.themeChangeObserver) {
+        return;
+      }

---

74-80: Tear down connector state to allow clean re-observe

When unobserving, also clear the themeChangeObserver property (and $connector if empty) so a subsequent observeThemeChange can re-initialize correctly.

Apply this diff:

-      if (markDownEditor?.$connector?.themeChangeObserver) {
-        markDownEditor.$connector.themeChangeObserver.disconnect();
-        markDownEditor.$connector.themeChangeObserver = null;
-      }
+      if (markDownEditor?.$connector?.themeChangeObserver) {
+        markDownEditor.$connector.themeChangeObserver.disconnect();
+        // Remove the observer reference to allow re-initialization later
+        delete markDownEditor.$connector.themeChangeObserver;
+        // If no other connector state is stored, clean up the namespace too
+        if (Object.keys(markDownEditor.$connector).length === 0) {
+          delete markDownEditor.$connector;
+        }
+      }

🧹 Nitpick comments (2)

src/main/resources/META-INF/resources/frontend/fcMarkdownEditorConnector.js (2)

51-53: Scope the MutationObserver to the ‘theme’ attribute only

Narrowing the observer to attributeFilter ['theme'] reduces noise and avoids callbacks for irrelevant attribute changes.

Apply this diff:

-      // options for the observer (which mutations to observe)
-      const config = { attributes: true };
+      // options for the observer (only watch the 'theme' attribute)
+      const config = { attributes: true, attributeFilter: ['theme'] };

Also applies to: 69-73

---

59-61: Remove debug logging

console.log in the hot path will spam the console on every theme change. Remove or downgrade to console.debug if needed.

Apply this diff:

-            console.log("theme", themeName);

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📥 Commits

Reviewing files that changed from the base of the PR and between 9400316 and 2e3d13e.

📒 Files selected for processing (1)

• src/main/resources/META-INF/resources/frontend/fcMarkdownEditorConnector.js (1 hunks)

🔇 Additional comments (1)

src/main/resources/META-INF/resources/frontend/fcMarkdownEditorConnector.js (1)

76-79: Null-safe disconnect via optional chaining looks good

Using optional chaining prevents the “Cannot read properties of null (reading '$connector')” error on detach. This directly addresses Issue #20 without changing behavior otherwise.