Was This An Unfair Search? Location: Texas

I got pulled over for a busted headlight and immediately after pulling over this cop somewhere up to me asking for id I give it over and apparently I was acting nervous which I can’t really say if I was or not I was trying my hardest to comply because I really had no business driving with my headlight busted and tried my hardest to comply and within 5 minutes they had me out of my car and calling a dog to search my car. I told them I didn’t want them searching my car beforehand when they asked and that’s when they called for a k-9. When the dog arrived they kept taping my trunk for the dog to sniff after the dog had already sniffed and went to sniff the rest of my car but for some reason they were really trying to get this dog to sniff my trunk and after the dog finally left my from trunk it then when to my passenger side and apparently alerted to something in that area which gave them cause to search I guess? I really had nothing in my car just two empty pre roll containers in my trunk that were empty that were legally purchased at a local smoke shop after they tore my car apart they found nothing obviously and let me go and I was just wondering how justified that is for the dog to alert not even in the area in my trunk to where I guess the dog could sniff the pre roll containers but instead they said if alerted to something in my passenger side idk much about law and was just wondering how legal that is or how often k-9s mess up or the handlers mess up when a dog alerts to something being in the car. Thanks to anyone who replies Location: Texas