Addressing 'Errors' in dataset with null values

Hello, when refreshing my dataset, I get thousands of 'Errors.'

These 'Errors' are due to:

1. The cells being empty. My dataset becomes too large and laggy if I replace all the blanks with 'null'.
2. A data type mismatch. For some columns, new data is different from the old data (e.g., was Text, now Whole Number). I don't need to reference these columns with mismatched types but I don't want to remove the columns in case there is a need in the future. 

It seems to give an 'Error' for rows even with data that I need. (Image 1 is PowerQuery; image 2 is my Excel sheet showing that there is data but it will show the whole row as 'Error'):

How can I best address these 'Errors' without removing the data that I do want to keep? Thanks for any pointers!