Sweet angel,
There's a simple explanation, but it requires a leap of faith: even lawyers have a sense of humor. (That is, if you regard puns as humorous.)
As has been pointed out by Hamlet35-2000 and others, Shakespeare's play is (and has always been) called "The Comedy of Errors." Helenabear refers to The American Heritage Dictionary, which notes that a "comedy of errors" is now idiom for a funny sequence of events, usually when the different people involved are working under false assumptions.
The term "comity of errors" is simply a pun on this idiom. (You may groan now.)
Any explanation of a pun takes away the fun. But since I'm a lawyer (who absolutely loves wordplay) - and since you ask - I'll give you the background. And if you don't like long explanations, stop reading now, and just take my word for it - "comity of errors" is not a recognized term, it is simply a pun that is used (rarely) by lawyers when they see the opportunity. (I'll ignore the possibility that someone honestly thinks that Shakepeare's play is called "The Comity of Errors" - after all, even lawyers do make mistakes.)
"Comity of errors" has been used in the title of at least two legal articles that I know of, and a google search found three articles in which it has been used at the very end of the article, as a punch-line. All these articles deal with the legal concept of comity. For lawyers, "comity" is simply a five-dollar word for courtesy and respect. One common legal meaning of comity is the willingness to grant a privilege, not as a matter of right, but out of deference and good will. A special sense of the word - and one that is used in most of these five articles - is that the courts of one jurisdiction should give effect to the laws and judicial decisions of another jurisdiction, not as a matter of obligation but out of deference and mutual respect.
Not to go into the legal details (not only are these boring, but each of the five articles dealt with different sets of circumstances), the authors tend to argue that, in the special case that they are writing about, the court was wrong in basing its decision on comity. Comity was used in error - hence the punch-line, a "comity of errors."
OK, class dismissed.