The word 'friend' in the sentence is used correctly. There is no error associated with the word 'friend' itself, but it is important to use the correct subject and object personal pronouns in sentences.
The question "My friend and I went out for ice cream yesterday. Which kind of error is in the word friend?" does not contain an error in the word 'friend.'
There is no grammatical or spelling error in the word as it is used correctly in the sentence as a singular noun to denote one person with whom the speaker has a relationship of mutual affection.
However, if the student is asking which kind of error could occur with a similar word, then a common mistake that can be made is confusing subject and object personal pronouns, such as using 'me' instead of 'I' or vice versa.
For example, it would be incorrect to say 'My friend and me went out for ice cream.'
An accurate sentence using the word 'friend' as a subject would be 'My friend and I ordered pizza for dinner.' Conversely, when using it as an object, the sentence would be 'The pizza was delivered to my friend and me.