Minification bug: erroneous fusion of operator symbols

Here's a example:

>(_=>print(x - --1))()
Uncaught Error: Unable to assign value to non-reference Number
 at line 1 col 10
print(x---1)

My code is indeed incorrect for the reason given, but the source snippet (if reparsed) is about x-- - 1, which is probably what I thought I had typed(!).