I support this because the error tag is too general, and should be broken down into the type of error as John suggests, which would help users to be more specific about what kind of error their question is about, helping readers to more easily recognize what the question is about too, and helping to improve the search and related question results as well.
I think the error-code tag has been under utilized (in only 3 questions) because it's also too vague, so we should further define that as
http-error-code (for HTTP errors that tags don't already exist) to make this tag clearer.
Then we could edit questions labeled with just the error tag to contain more specific error tags, including:
code-errors (e.g., for scripting and other code)
application errors (e.g., for applications, frameworks, control panels, etc... that don't already have tags)