cue/load: avoid "user:" and "instance:" error prefixes
The `cue/load` package currently creates errors with `user:` and/or
`instance:` prefixes, which might make sense in the context of
the Go API, but don't really make sense on the command line,
as evidenced by comments like this:
https://review.gerrithub.io/c/cue-lang/cue/+/1194664/8/cmd/cue/cmd/testdata/script/issue174.txtar
This change removes those prefixes.
This doesn't appear to be covered by any tests, although
these prefixes do show up in some errors printed by a later
CL, which this improves.
Signed-off-by: Roger Peppe <rogpeppe@gmail.com>
Change-Id: I66670e94c4bd0a45d84a2ed4d6dec6de8d9db758
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1194762
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>
Unity-Result: CUE porcuepine <cue.porcuepine@gmail.com>