Added documentation to errors reading JSON that explains how to find the root cause of the error. The problem is that any issue in the subprocess call will return the same cryptic error, so it's difficult to debug. Perhaps it's possible to make this give a better error message in Emacs itself, but doing that across the various places JSON can be read would be challenging: it's good to have a documentation snippet about it in that case.
Added documentation to errors reading JSON that explains how to find the root cause of the error. The problem is that any issue in the subprocess call will return the same cryptic error, so it's difficult to debug. Perhaps it's possible to make this give a better error message in Emacs itself, but doing that across the various places JSON can be read would be challenging: it's good to have a documentation snippet about it in that case.