Is it wrong to be mad at my dog?

I love my doggies so much but I swear sometimes they are more work and stress than my 18 month-old. Today my older dog (5 years) ate a slice of chocolate chip banana bread when I left the room for not even a minute. He normally never goes after food like that so I wasn’t expecting it... maybe it’s being pregnant and emotional but I was so mad. For a while I was more angry than concerned. I sent him outside so I could cool off and figure out what to do. The thing is, I know he doesn’t always get it that it’s wrong, but is it ok to be angry and upset? I was pretty stoked about that banana bread. :(

Also, should I be concerned? It was a smaller slice but it was semi-sweet chocolate chips and I’ve heard those can be more dangerous. I’m trying to get him to drink lots of water. I have nothing to induce vomiting with.