Frankly, when I have to start lying to players and shouting at them, I feel like I'm sucking at my job.
Frequently due to the fact that the players are sucking at theirs, wouldn't you agree? At least in my experience, every time I've seen a flustered DM, I've seen some pretty asinine players driving them up that wall.
Roleplaying should be a collaborative game of players plus DM, not players vs DM.
I come from a group that is very pro-player. As in, it's honestly more important to empower the players than empower yourself as the GM. I'm not 100% sold on the concept, but I've come to accept that without some chaos from your players, a game becomes stagnant. Deciding what's worth embracing and running with, and what's not, is the hard part of being a GM. Generally though, I've tried to get away from casting what players do as "asinine." I game with adults only these days, and while they can act fairly immature sometimes, I try to respect what they bring to the table, because players are ultimately what makes a game come to life. You can create as many NPCs and fantastical descriptions as you want as a GM, but without that element of player chaos, you're essentially asking people to roll dice whilst you read them your novel.
That said, yes. Often panic comes in because players, as a rule I think, like "breaking shit." Be it the rules, your carefully crafted setting, your NPCs or just your expectations. The difference is, I've come to believe that is pretty much their function in game. You create something, they break it, and when you've rebuilt it you've arrived at that synthesis between GM plan and player action. The trick for the GM, ultimately, is confidence. If you ACT like you own the situation that's been created, the players give you credit for it. Regardless of whether you're actually the reason it happened, or not.
This is why improv GMs get a little more credit than world builders I think. Good improv GMs can make it look like they planned it all along and it seems like an amazing feat to players. World builders deliberately try to make it all planned out and effectively lay their cards out at the start of the adventure. And when things invariably go differently than they planned....they look reactive instead of proactive, like they didn't really have control over the situation to begin with.