Wording of one particular error message may be vague.

[brianbancroft]

When testing https://cbers-stac.s3.amazonaws.com/CBERS4/MUX/057/122/catalog.json, the first error message that comes up is as follows:

'stac_version' is a required property of []

This might be a bit too vague, and may confuse some under-caffeinated, but otherwise-diligent individuals.

[m-mohr]

Does is get better if you add a "const": "0.6.2" to the stac_version field in the schema? I already wondered whether we should include this in the JSON schema anyway as for each released version there's exactly one value we except. See: radiantearth/stac-spec#398