refactor(superdoc): guard nullable toolbar accesses (SD-2867 phase B) (#3069)

* refactor(superdoc): guard nullable toolbar accesses (SD-2867 phase B)

* fix(superdoc): clarify toolbar guard rationale comments (SD-2867 phase B)

Author: caio-pizzol

packages/superdoc/src/core/SuperDoc.js

@@ -1189,7 +1189,14 @@ export class SuperDoc extends EventEmitter {
     this.toolbar = new SuperToolbar(config);
 
     this.toolbar.on('exception', this.config.onException);
-    this.once('editorCreate', () => this.toolbar.updateToolbarState());
+    // `this.toolbar` infers as `SuperToolbar | null` from the field's
+    // first assignment in `#addToolbar` (the `null` placeholder a few
+    // lines up). The closure registers after the SuperToolbar instance
+    // is in place and reads `this.toolbar` at emission time, so under
+    // normal flow it will see the live instance; the optional chain
+    // is here to satisfy TS's typedef and to no-op if a future
+    // `destroy()` ever clears the field.
+    this.once('editorCreate', () => this.toolbar?.updateToolbarState());
   }
 
   /**
@@ -1421,7 +1428,14 @@ export class SuperDoc extends EventEmitter {
   }
 
   #setModeViewing() {
-    this.toolbar.activeEditor = null;
+    // `this.toolbar` infers as `SuperToolbar | null` from the field's
+    // first assignment in `#addToolbar` (the `null` placeholder before
+    // the SuperToolbar is constructed). `#addToolbar` runs once during
+    // init and unconditionally installs the instance, so by the time
+    // mode changes are reachable the toolbar is non-null. The guard
+    // keeps TS satisfied and stays a no-op if a future destroy/teardown
+    // ever clears the field.
+    if (this.toolbar) this.toolbar.activeEditor = null;
 
     const commentsVisible = this.config.comments?.visible === true;
     const trackChangesVisible = this.config.trackChanges?.visible === true;