Fix markdown preview refresh command potentially resetting preview scroll...

Fix markdown preview refresh command potentially resetting preview scroll position to top if focused on preview

Fixes #80680

extensions/markdown-language-features/src/features/preview.ts

@@ -288,12 +288,15 @@ export class MarkdownPreview extends Disposable {
 		const editor = vscode.window.activeTextEditor;
 		// Reposition scroll preview, position scroll to the top if active text editor
 		// doesn't corresponds with preview
-		if (editor && editor.document.uri.fsPath === resource.fsPath) {
-			this.line = getVisibleLine(editor);
-		} else {
-			this.line = 0;
+		if (editor) {
+			if (editor.document.uri.fsPath === resource.fsPath) {
+				this.line = getVisibleLine(editor);
+			} else {
+				this.line = 0;
+			}
 		}
 
+
 		// If we have changed resources, cancel any pending updates
 		const isResourceChange = resource.fsPath !== this._resource.fsPath;
 		if (isResourceChange) {