Different missing key zero behaviour with data.CSVByRow vs coll.Slice (coll.Dict ...) (coll.Dict ...)

[safferyj]

With missingkey.tmpl:

{{$csv := 
`lang,keywords
C,32
Go,25
COBOL,357` -}}

{{- $c := ($csv | data.CSVByRow)}}
$c: {{$c}}

{{- $d := coll.Slice (coll.Dict "lang" "C" "keywords" "32") (coll.Dict "lang" "Go" "keywords" "25") (coll.Dict "lang" "COBOL" "keywords" "357")}}
$d: {{$d}}

{{$testTemplate := `{{range . -}}
{{.lang }} has {{ .keywords }} keywords.
[{{.missingKey}}] does not exist.
{{if .missingKey}}bad{{else}}good{{end}}
{{if .missingKey | strings.TrimSpace}}bad{{else}}good{{end}}
{{if $x := .missingKey | strings.TrimSpace}}bad{{else}}good{{end}}
{{end}}` -}}

Render $c:
{{tmpl.Inline $testTemplate $c}}
Render $d:
{{tmpl.Inline $testTemplate $d}}

Execution of gomplate --missing-key zero -f missingkey.tmpl with 4.1.0 generates the following output:

$c: [map[keywords:32 lang:C] map[keywords:25 lang:Go] map[keywords:357 lang:COBOL]]
$d: [map[keywords:32 lang:C] map[keywords:25 lang:Go] map[keywords:357 lang:COBOL]]

Render $c:
C has 32 keywords.
[] does not exist.
good
good
good
Go has 25 keywords.
[] does not exist.
good
good
good
COBOL has 357 keywords.
[] does not exist.
good
good
good

Render $d:
C has 32 keywords.
[<no value>] does not exist.
good
bad
bad
Go has 25 keywords.
[<no value>] does not exist.
good
bad
bad
COBOL has 357 keywords.
[<no value>] does not exist.
good
bad
bad

See also discussion #2215.

[safferyj]

I notice that the types of $c and $d are different. Adding

$c: {{printf "%T" $c}}
$d: {{printf "%T" $d}}

to the template results in the following additional output

$c: []map[string]string
$d: []interface {}