Fix quick chat layout (microsoft#232167)

Fix microsoft#232096

Author: roblourens

src/vs/workbench/contrib/chat/browser/chatListRenderer.ts

@@ -624,6 +624,13 @@ export class ChatListItemRenderer extends Disposable implements ITreeRenderer<Ch
 			} else {
 				// Nothing new to render, stop rendering until next model update
 				this.traceLayout('doNextProgressiveRender', 'caught up with the stream- no new content to render');
+
+				if (!templateData.renderedParts) {
+					// First render? Initialize currentRenderedHeight. https://github.com/microsoft/vscode/issues/232096
+					const height = templateData.rowContainer.offsetHeight;
+					element.currentRenderedHeight = height;
+				}
+
 				return true;
 			}
 		}
@@ -635,7 +642,7 @@ export class ChatListItemRenderer extends Disposable implements ITreeRenderer<Ch
 		const height = templateData.rowContainer.offsetHeight;
 		element.currentRenderedHeight = height;
 		if (!isInRenderElement) {
-			this._onDidChangeItemHeight.fire({ element, height: templateData.rowContainer.offsetHeight });
+			this._onDidChangeItemHeight.fire({ element, height });
 		}
 
 		return false;