(Null problem) 'A point in the grid is null' in 'Surface From Points'

I am making terrain in grasshopper with SHP file. While doing ‘Mesh | Ray’ to ‘Surface From Points’, it show error with the sign ’ ‘A point in the grid is null. Fitting operation abortted’.
I noticed some of the data were . And I don’t know how to handle with this. Please tell me how to do!

Question_Surface From Points Error(null).3dm (2.4 MB)
Question_Surface From Points Error(null).gh (20.8 KB)
N3L_F0010000_F001_000000.dbf (182.7 KB)
N3L_F0010000_F001_000000.shp (3.4 MB)
N3L_F0010000_F001_000000.shx (4.1 KB)