Unused variable incorrectly reported by `jsonnet-lint`

[nkuln]

Looks like the circumstance is very specific -- when the var is being used in an assert statement as part of an object.

Expectation: jsonnet-lint does not report any error in this source file.
Actual: jsonnet-lint reports unused variable error
Details:

% cat assert_lint.jsonnet
local myvar = 'xxxxx';

{
  assert std.length(myvar) == 5 : 'yyyyy',
  some_field: 'zzzzz',
}

% jsonnet-lint --version
Jsonnet linter v0.20.0

% jsonnet-lint assert_lint.jsonnet
assert_lint.jsonnet:1:7-22 Unused variable: myvar

local myvar = 'xxxxx';


Problems found!