Removes all errors recorded with environment env which are as serious as severity, or less serious.

severity must be one of NOTHING_ERR, REPORT_ERR, NOTICE_ERR, WARNING_ERR, ERROR_ERR, XXX_ERR (for a description of these see ErrorSeverity_ns). Pass XXX_ERR to clear them all.

The memory used by the error reports is freed, so if you previously used GetError_ns to obtain pointers to some of them, you must not use these pointers any more (for example, don't try to call ClearError_ns, or ErrorMessage_ns with one of them).

The name of this function is very similar to ClearError_ns, but hopefully there won't be any confusion since its arguments are so different.

Remember that just because you clear away the error reports doesn't mean that the problems that caused them have necessarily gone away!

Multithreading Note. In a multithreading environment, ClearErrors_ns is well-behaved in that it only clears the errors that were caused by the current (the calling) thread.