Fatal error when decoding an array with a NULL value in it

[vzsg]

Apparently, Postgres encodes NULL values inside arrays in a way that PostgreSQLDataDecoder does not anticipate. In this case, the byte count of the value is -1, which causes this line called from here to explode with a friendly error:

Fatal error: Can't form Range with upperBound < lowerBound

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While this originally was discovered by using the array_agg function combined with left joins (which triggers this weird behavior), there is a much simpler reproduction:

conn.raw("SELECT ARRAY[NULL, 'foo', NULL, 'bar'] AS arr")
    .all(decoding: SimpleArray.self)

where SimpleArray is defined as:

struct SimpleArray: Decodable {
    let arr: [String?]
}

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The issue was discovered with Vapor 3 / Postgres (driver) 1.4.1.

V4 doesn't seem to be affected as array decoding is not implemented at all at the time of writing.