Please solve the programming task below using a self-contained code snippet in a markdown code block.

Given a binary array nums, you should delete one element from it.
Return the size of the longest non-empty subarray containing only 1's in the resulting array. Return 0 if there is no such subarray.
 
Please complete the following python code precisely:
```python
class Solution:
    def longestSubarray(self, nums: List[int]) -> int:
```