Don't try parsing `undefined` as json

Fixes #45804

src/vs/editor/contrib/suggest/suggestMemory.ts

@@ -192,7 +192,9 @@ export class SuggestMemories {
 
 		try {
 			const raw = this._storageService.get(`${this._storagePrefix}/${this._mode}`, StorageScope.WORKSPACE);
-			this._strategy.fromJSON(JSON.parse(raw));
+			if (raw) {
+				this._strategy.fromJSON(JSON.parse(raw));
+			}
 		} catch (e) {
 			// things can go wrong with JSON...
 		}