What is the NS_ERROR_INVALID_POINTER error in Firefox?

Question

While testing JavaScript code in Firefox 3.5 I sometimes get the following error:

Component returned failure code: 0x80004003 (NS_ERROR_INVALID_POINTER)

I've tried Googling it, but all I can find are solutions to specific problems in other people's code (ie. "if you do this differently then the error will not occur"). But what I'd like to understand is: what is that error - what does it mean? In other words, what do I really know from that error and what do I need to guess?

Answer 1

Without knowing specifically what you are calling, the error generally means you've passed something null to something that does not expect a null value.