Many European states other than USSR made non-aggression pacts with Nazi Germany:
- Poland [1]
- Estonia [2]
- Latvia [3]
- UK, France, Italy [4]
It is important to note that all of these pacts were made prior to the Molotov-Ribbentrop pact.
Your comment misrepresents the historical situation, which is that USSR observed many powerful Euro countries making agreements with Nazi Germany, and Stalin realised that USSR would be on their own in a war with Germany. Which is in fact what happened.
Not just non-aggression - Poland, in particular, directly participated in the partitioning of Czechoslovakia under the Munich Agreement, forcibly annexing parts of its territory under the threat of a military invasion.
Poland fought Germans in 1939, so the USSR wasn't "alone in their own war with Germany". It was just that the USSR decided to invade Poland instead of joining the fight against Germans in 1939.