Refuse to send replies with an unknown inline snippet

This behavior can be disabled by setting the following option:
errorOnUnknownInlineSnippet = off

CHANGELOG.md

@@ -11,6 +11,7 @@ Please report any bugs you encounter by [creating a GitHub issue](https://github
   * E.g. `!r Hello! {{rules}}`
   * The symbols used can be changed with the `inlineSnippetStart` and `inlineSnippetEnd` options
   * This feature can be disabled by setting `allowInlineSnippets = off` in your config
+  * By default, the bot will refuse to send a reply with an unknown inline snippet. To disable this behavior, set `errorOnUnknownInlineSnippet = off`.
 * Plugins can now also be installed from NPM modules
   * Example: `plugins[] = npm:some-plugin-package`
 * Fix occasional bug with expiring blocks where the bot would send the expiry message multiple times

docs/configuration.md

@@ -168,6 +168,11 @@ commandAliases.x = close
 **Default:** `off`  
 When enabled, the bot will send a greeting DM to users that join the main server.
 
+#### errorOnUnknownInlineSnippet
+**Default:** `on`  
+When enabled, the bot will refuse to send any reply with an unknown inline snippet.  
+See [allowInlineSnippets](#allowInlineSnippets) for more details.
+
 #### greetingAttachment
 **Default:** *None*  
 Path to an image or other attachment to send as a greeting. Requires `enableGreeting` to be enabled.

src/data/Thread.js

@@ -206,14 +206,24 @@ class Thread {
         return _map;
       }, {});
 
+      let unknownSnippets = new Set();
       text = text.replace(
         new RegExp(`${config.inlineSnippetStart}(\\s*\\S+?\\s*)${config.inlineSnippetEnd}`, "i"),
         (orig, trigger) => {
           trigger = trigger.trim();
           const snippet = snippetMap[trigger.toLowerCase()];
+          if (snippet == null) {
+            unknownSnippets.add(trigger);
+          }
+
           return snippet != null ? snippet.body : orig;
         }
       );
+
+      if (config.errorOnUnknownInlineSnippet && unknownSnippets.size > 0) {
+        this.postSystemMessage(`The following snippets used in the reply do not exist:\n${Array.from(unknownSnippets).join(", ")}`);
+        return false;
+      }
     }
 
     // Prepare attachments, if any

src/data/cfg.jsdoc.js

@@ -59,6 +59,7 @@
  * @property {boolean} [allowInlineSnippets=true]
  * @property {string} [inlineSnippetStart="{{"]
  * @property {string} [inlineSnippetEnd="}}"]
+ * @property {boolean} [errorOnUnknownInlineSnippet=true]
  * @property {string} [logStorage="local"]
  * @property {object} [logOptions]
  * @property {string} logOptions.attachmentDirectory

src/data/cfg.schema.json

@@ -331,6 +331,11 @@
       "default": "}}"
     },
 
+    "errorOnUnknownInlineSnippet": {
+      "$ref": "#/definitions/customBoolean",
+      "default": true
+    },
+
     "logStorage": {
       "type": "string",
       "default": "local"