I'm trying to find area covered by plants on my study area. please make correction if needed the code link is here: https://code.earthengine.google.com/15024379590dfebb0ce49ffdfd56ecd4

I'm trying to find area covered by plants on my study area, but I'm getting this error:

ndvi.filterDate is not a function

This is my code:

Code link is here: https://code.earthengine.google.com/15024379590dfebb0ce49ffdfd56ecd4

I'm trying to find area covered by plants on my study area. please make correction if needed the code link is here: https://code.earthengine.google.com/15024379590dfebb0ce49ffdfd56ecd4