feat(prettier): Allow a Prettier instance to be optional

.gitignore

@@ -4,3 +4,4 @@ node_modules
 *.js
 *.map
 *.tgz
+.DS_Store

packages/prettier/index.ts

@@ -44,6 +44,10 @@ export function create(
 		 */
 		prettier?: typeof import('prettier') | undefined;
 		getPrettier?: (serviceEnv: ServiceEnvironment) => typeof import('prettier') | undefined,
+		/**
+		 * If true, the plugin will not throw an error if it can't load Prettier either through the `prettier`, or `getPrettier` properties or through a normal `import('prettier')`.
+		 */
+		allowImportError?: boolean;
 	} = {},
 	getPrettierConfig = async (filePath: string, prettier: typeof import('prettier'), config?: ResolveConfigOptions) => {
 		return await prettier.resolveConfig(filePath, config) ?? {};
@@ -52,19 +56,30 @@ export function create(
 	return {
 		name: 'prettier',
 		create(context): ServicePluginInstance {
+			const languages = options.languages ?? ['html', 'css', 'scss', 'typescript', 'javascript'];
 
-			let prettier: typeof import('prettier');
+			let prettier = options.prettier;
 			try {
-				prettier = options.prettier
-					?? options.getPrettier?.(context.env)
-					?? require('prettier');
-			} catch (e) {
-				throw new Error("Could not load Prettier: " + e);
+				if (!prettier) {
+					if (options.getPrettier) {
+						prettier = options.getPrettier(context.env);
+					} else {
+						prettier = require('prettier');
+					}
+				}
+			} catch (error) {
+				if (!options.allowImportError) {
+					throw new Error("Could not load Prettier: ");
+				};
+			}
+
+			if (!prettier) {
+				return {};
 			}
-			const languages = options.languages ?? ['html', 'css', 'scss', 'typescript', 'javascript'];
 
 			return {
 				async provideDocumentFormattingEdits(document, _, formatOptions) {
+					if (!prettier) return;
 					if (!languages.includes(document.languageId)) {
 						return;
 					}