So... creating a DynamoDB table leads to this:

Diagnostics:
  aws:dynamodb:Table: Weblab
    error: Plan apply failed: ValidationException: One or more parameter values were invalid: Some index key attributes are not defined in AttributeDefinitions. Keys: [weblab,, revision], AttributeDefinitions: [latest, weblab, revision]
    	status code: 400, request id: OR00VLUOA2V4LMU1CV4MLC9ITFVV4KQNSO5AEMVJF66Q9ASUAAJG

My table spec is:

// Create a Weblab table
const table = new aws.dynamodb.Table("Weblab", {
    attributes: [
        {
            name: "weblab",
            type: "S"
        },
        {
            name: "revision",
            type: "N"
        },
        {
            name: "latest",
            type: "N"
        }
    ],
    rangeKey: "revision",
    hashKey: "weblab",
    globalSecondaryIndexes: [
        {
            name: "revision-index",
            hashKey: "revision",
            rangeKey: "weblab,",
            projectionType: "INCLUDE",
            nonKeyAttributes: [
                "description"
            ],
            readCapacity: 5,
            writeCapacity: 5
        },
        {
            name: "latest-index",
            hashKey: "latest",
            rangeKey: "weblab",
            projectionType: "INCLUDE",
            nonKeyAttributes: [
                "revision",
                "activations"
            ],
            readCapacity: 5,
            writeCapacity: 5
        }
    ],
    readCapacity: 5,
    writeCapacity: 5,
    serverSideEncryption: {
        enabled: true
    },
    pointInTimeRecovery: {
      enabled: true
    }
});

Somewhere there's a blank index key being injected. Can't figure out where.