Build-Documentation Silently Outputs Nothing if `formats` missing from config.json

[RichardSlater]

Description

If formats is missing or empty in the docs JSON file then Build-Documentation silently fails.

Example Broken Config

{
    "title": "Stacks Infrastructure AKS",
    "output": "{{ basepath }}/outputs/docs/{{ format }}",
    "trunkBranch": "main",
    "path": "{{ basepath }}/docs/index.adoc",
    "libs": [
        "asciidoctor-diagram"
    ],
    "pdf": {
        "attributes": [
            "pdf-theme={{ basepath }}/build/config/pdf/theme.yml",
            "pdf-fontsdir=\"{{ basepath }}/docs/styles/fonts;GEM_FONTS_DIR\"",
            "allow-uri-read",
            "blockdiag=/usr/bin/blockdiag",
            "skip-front-matter",
            "graphvizdot=/usr/bin/dot"
        ]
    },
    "html": {
        "attributes": [
            "stylesheet={{ basepath }}/conf/html/style.css",
            "allow-uri-read",
            "toc=left",
            "java=/usr/bin/java",
            "graphvizdot=/usr/bin/dot",
            "skip-front-matter"
        ]
    }
}

Example Fixed Config

{
    "title": "Stacks Infrastructure AKS",
    "output": "{{ basepath }}/outputs/docs/{{ format }}",
    "trunkBranch": "main",
    "path": "{{ basepath }}/docs/index.adoc",
    "formats": [
        "pdf",
        "html"
    ],
    "libs": [
        "asciidoctor-diagram"
    ],
    "pdf": {
        "attributes": [
            "pdf-theme={{ basepath }}/build/config/pdf/theme.yml",
            "pdf-fontsdir=\"{{ basepath }}/docs/styles/fonts;GEM_FONTS_DIR\"",
            "allow-uri-read",
            "blockdiag=/usr/bin/blockdiag",
            "skip-front-matter",
            "graphvizdot=/usr/bin/dot"
        ]
    },
    "html": {
        "attributes": [
            "stylesheet={{ basepath }}/conf/html/style.css",
            "allow-uri-read",
            "toc=left",
            "java=/usr/bin/java",
            "graphvizdot=/usr/bin/dot",
            "skip-front-matter"
        ]
    }
}