The learner makes this error.
Whenever she says the name of a person she uses the definite article. For example…

She uses the definite article for all the other definite objects. While people are definite objects, in English we generally don't use the definite article with people's names.

What kind of error is this?

Research from Hakuta (1974) has found that Japanese people learn articles slower than language learners from first language backgrounds that have articles (e.g. Spanish). This seems to be a deviation from the morpheme order discovered by Dulay and Burt (1974).

According to this data, what kind of error is it when a Japanese person has difficulty learning English articles?

All language learners have difficulty with the English third person singular 's' morpheme even if their first language has a similar form.

Some researchers believe this form is difficult to acquire because it is not salient, & relatively meaningless.  In other words, it is hard for the learner to hear and also hard to notice or pay attention to because it doesn't really affect the meaning of the input.

For this same reason, learners are very rarely corrected when forgetting to use this morpheme. In fact, many native speakers won't even notice if it is missing, especially if you speak quickly. It does not affect the meaning of the sentence.

How would you classify these problems?

An English language learner makes the following error:

The reason why is because in his English class the teacher gave him a list of adjectives that he must memorize, but didn't give him any dialogue, text, or model sentences for them. On the top of the list was a slot filling exercise ---

Each adjective can supposedly be used to fill that slot... for example,

Why does the learner make this error?
Where has his error come from?

The student says

This error has a very nasty sexual meaning. Very naughty!

He is using the adjective "hard" the same way he uses sad, tired, frustrated, anxious or nervous, and doesn't know that this adjective follows different rules.

He has never been taught to do this incorrect usage - it is a product of his own system.

What kind of error is this?

An American is out walking with a Korean friend and they need to buy some medicine. There are two pharmacies on the street. One is close, but the other is farther down the street. The American asks his Korean friend which pharmacy they should go to. She says, "Let’s go down pharmacy", and points down the street.

She says this because she doesn’t know how to make relative clauses with prepositions such as "the pharmacy down the street".

What kind of error is this?

A Korean woman is in the kitchen with her American friend. She wants to ask her to give her the cup on the table. She doesn’t know how to say that, so instead she just says, "Give me table cup", and points.

What kind of error is this?