KeyError: 'i' and  Error
The dictionary word2id does not contain the word "i". I can run the Kaggle Kernel and do not get the error. 
When I run the code my word2id dictionary looks like this:

{'i': 0,
 'feel': 1,
 'awful': 2,
 'about': 3,
 'it': 4,
 'too': 5,
 'because': 6,...}


The word "i" is definitely in there, I think you did not run the code to create the word2id dictionary properly. Make sure to run all the cells of the kernel.