Take a look at the sentence again:
Jeremiah likes to put peanut butter on his pancakes instead of
syrup, the smell is appealing, but I wouldn't
want to eat anything so sticky that early in the morning.
The problem occurs between syrup and the. Jeremiah likes to put peanut butter on his pancakes instead of syrup is a complete sentence. The smell is appealing is the next complete sentence. Because these two parts have just a comma between them, they create a comma splice, a major sentence error.
To fix the problem, you could put a period after syrup and then capitalize the T for the.