Also change the variable name used to keep the Exception returned from "err" to
"exc".
This uncovers several error scenarios that were not returning Exception, and
would result in the absense of stack traces when such errors occur.
In addition to an uncontroversial spelling fix this addresses several,
related, warnings produced by the `golint` tool. In general I agree with
golint that unnecessary "else" blocks should be avoided. So this change
refactors those cases.
Note: I recognize that `golint` is deprecated (see
https://github.com/golang/go/issues/38968) since it is no longer being
maintained and there is controversy about its set of warnings. Nonetheless,
it appears that the warnings it emits for this project are all reasonable
and actionable with one potential exception: the naming of the `map_`
method in pkg/eval/compile_value.go.
This avoids race conditions of accessing the local scope. The test case
"x = 1", "put $x | y = (all)" used to contain a race condition but no longer
does.
This addresses #73.
