What is generally happening in these cases is that data is getting stringified, with `null` becoming the string "null" (which is a common output for string form

What is generally happening in these cases is that data is getting stringified, with `null` becoming the string "null" (which is a common output for string formatting a null in various languages). This output is is then later re-parsed, and to try to restore null inputs back to being null, the code matches on the string "null", ignoring the fact that that could have been a valid string itself.