When trying to execute a MCP tool using MCP Inspector version 0.17, if the tool has a parameter with null default value, then default HTML input is empty (as before), but when executing there is an error on Chrome/Safari.

On Safari it looks like this:

I tested on Chrome as well, the bug appears too (I am running macOS).

If I manually set the field to null, then it works. On MCP Inspector 0.16, those default values were handled automatically.
If you have a tool with lots of default null values, filling everything manually can quite quite long.