Misc config loading fixes

The main motivation behind this is simplicity and correctnes, but the new small config library is also faster:

```
BenchmarkDefaultConfigProvider/Viper-16         	  252418	      4546 ns/op	    2720 B/op	      30 allocs/op
BenchmarkDefaultConfigProvider/Custom-16        	  450756	      2651 ns/op	    1008 B/op	       6 allocs/op
```

Fixes #8633
Fixes #8618
Fixes #8630
Updates #8591
Closes #6680
Closes #5192

config.toml

@@ -7,7 +7,7 @@ footnotereturnlinkcontents = "↩"
 languageCode = "en-us"
 title = "Hugo"
 
- ignoreErrors = ["error-remote-getjson"]
+ ignoreErrors = ["error-remote-getjson", "err-missing-instagram-accesstoken"]
 
 
 googleAnalytics = "UA-7131036-4"

content/en/getting-started/configuration.md

@@ -80,6 +80,26 @@ Considering the structure above, when running `hugo --environment staging`, Hugo
 {{% note %}}
 Default environments are __development__ with `hugo server` and __production__ with `hugo`.
 {{%/ note %}}
+
+## Merge Configuration from Themes
+
+{{< new-in "0.84.0" >}} The configuration merge described below was improved in Hugo 0.84.0 and made fully configurable. The big change/improvement was that we now, by default, do deep merging of `params` maps from themes.
+
+The configuration value for `_merge` can be one of:
+
+none
+: No merge.
+
+shallow
+: Only add values for new keys.
+
+shallow
+: Add values for new keys, merge existing.
+
+Note that you don't need to be so verbose as in the default setup below; a `_merge` value higher up will be inherited if not set.
+
+{{< code-toggle config="mergeStrategy" skipHeader=true />}}
+
 ## All Configuration Settings
 
 The following is the full list of Hugo-defined variables with their default

data/docs.json

@@ -1587,6 +1587,65 @@
         "preserveTOC": false
       }
     },
+    "mergeStrategy": {
+      "build": {
+        "_merge": "none"
+      },
+      "caches": {
+        "_merge": "none"
+      },
+      "frontmatter": {
+        "_merge": "none"
+      },
+      "imaging": {
+        "_merge": "none"
+      },
+      "languages": {
+        "_merge": "none",
+        "en": {
+          "_merge": "none",
+          "menus": {
+            "_merge": "shallow"
+          },
+          "params": {
+            "_merge": "deep"
+          }
+        }
+      },
+      "markup": {
+        "_merge": "none"
+      },
+      "mediatypes": {
+        "_merge": "shallow"
+      },
+      "menus": {
+        "_merge": "shallow"
+      },
+      "minify": {
+        "_merge": "none"
+      },
+      "module": {
+        "_merge": "none"
+      },
+      "outputformats": {
+        "_merge": "shallow"
+      },
+      "params": {
+        "_merge": "deep"
+      },
+      "permalinks": {
+        "_merge": "none"
+      },
+      "related": {
+        "_merge": "none"
+      },
+      "sitemap": {
+        "_merge": "none"
+      },
+      "taxonomies": {
+        "_merge": "none"
+      }
+    },
     "minify": {
       "minifyOutput": false,
       "disableHTML": false,

layouts/shortcodes/code-toggle.html

@@ -5,6 +5,9 @@
   {{ $sections := (split . ".") }}
   {{ $configSection := index $.Site.Data.docs.config $sections }}
   {{ $code = dict $sections $configSection  }}
+  {{ if $.Get "skipHeader"}}
+    {{ $code = $configSection  }}
+  {{ end }}
 {{ else }}
   {{ $code = $.Inner }}
 {{ end  }}
@@ -12,10 +15,15 @@
 <div class="code relative" {{ with $file }}id="{{ . | urlize}}"{{ end }}>
   <div class="code-nav flex flex-nowrap items-stretch">
     {{- with $file -}}
-			<div class="san-serif f6 dib lh-solid pl2 pv2 mr2">{{ . }}.</div>
+      <div class="san-serif f6 dib lh-solid pl2 pv2 mr2">
+        {{ . }}.
+      </div>
     {{- end -}}
     {{ range $langs }}
-			<button data-toggle-tab="{{ . }}" class="tab-button {{ cond (eq . "yaml") "active" ""}} ba san-serif f6 dib lh-solid ph2 pv2">{{ . }}</button>&nbsp;
+      <button data-toggle-tab="{{ . }}" class="tab-button {{ cond (eq . "yaml") "active" ""}} ba san-serif f6 dib lh-solid ph2 pv2">
+        {{ . }}
+      </button>
+      &nbsp;
     {{ end }}
   </div>
   <div class="tab-content">
@@ -24,8 +32,7 @@
         {{ highlight ($code | transform.Remarshal . | safeHTML) . ""}}
       </div>
       {{ if ne ($.Get "copy") "false" }}
-				<button class="needs-js copy copy-toggle bg-accent-color-dark f6 absolute top-0 right-0 lh-solid hover-bg-primary-color-dark bn white ph3 pv2" title="Copy this code to your clipboard." data-clipboard-action="copy" aria-label="copy button">
+        <button class="needs-js copy copy-toggle bg-accent-color-dark f6 absolute top-0 right-0 lh-solid hover-bg-primary-color-dark bn white ph3 pv2" title="Copy this code to your clipboard." data-clipboard-action="copy" aria-label="copy button"></button>
-				</button>
         {{/* Functionality located within filesaver.js The copy here is located in the css with .copy class so it can be replaced with JS on success */}}
       {{end}}
     {{ end }}