tolerate empty _quarto.yml file

Author: jjallaire

src/core/schema/validated-yaml.ts

@@ -23,6 +23,7 @@ export async function readAndValidateYamlFromFile(
   file: string,
   schema: Schema,
   errorMessage: string,
+  defaultContents?: string,
 ): Promise<unknown> {
   if (!existsSync(file)) {
     throw new Error(`YAML file ${file} not found.`);
@@ -33,8 +34,13 @@ export async function readAndValidateYamlFromFile(
     shortFileName = relative(Deno.cwd(), shortFileName);
   }
 
+  let fileContents = Deno.readTextFileSync(file).trimEnd();
+  if ((fileContents.trim().length === 0) && defaultContents) {
+    fileContents = defaultContents;
+  }
+
   const contents = asMappedString(
-    Deno.readTextFileSync(file).trimEnd(),
+    fileContents,
     shortFileName,
   );
   const {

src/project/project-context.ts

@@ -76,6 +76,7 @@ import { readAndValidateYamlFromFile } from "../core/schema/validated-yaml.ts";
 
 import { getProjectConfigSchema } from "../core/lib/yaml-schema/project-config.ts";
 import { getFrontMatterSchema } from "../core/lib/yaml-schema/front-matter.ts";
+import { kDefaultProjectFileContents } from "./types/project-default.ts";
 
 export function deleteProjectMetadata(metadata: Metadata) {
   // see if the active project type wants to filter the config printed
@@ -123,6 +124,7 @@ export async function projectContext(
         configFile,
         configSchema,
         errMsg,
+        kDefaultProjectFileContents,
       )) as ProjectConfig;
       projectConfig.project = projectConfig.project || {};
       const includedMeta = await includedMetadata(

src/project/project-index.ts

@@ -27,12 +27,13 @@ import { fileExecutionEngine } from "../execute/engine.ts";
 import { projectConfigFile, projectOutputDir } from "./project-shared.ts";
 import { projectScratchPath } from "./project-scratch.ts";
 import { parsePandocTitle } from "../core/pandoc/pandoc-partition.ts";
-import { readYaml } from "../core/yaml.ts";
+import { readYamlFromString } from "../core/yaml.ts";
 import { formatKeys } from "../config/metadata.ts";
 import {
   formatsPreferHtml,
   normalizeWebsiteFormat,
 } from "./types/website/website-config.ts";
+import { kDefaultProjectFileContents } from "./types/project-default.ts";
 
 export interface InputTargetIndex extends Metadata {
   title?: string;
@@ -119,7 +120,11 @@ export function readInputTargetIndex(
     const formats = Object.keys(index.formats);
     const projConfigFile = projectConfigFile(projectDir);
     if (projConfigFile) {
-      const config = readYaml(projConfigFile) as Metadata;
+      let contents = Deno.readTextFileSync(projConfigFile);
+      if (contents.trim().length === 0) {
+        contents = kDefaultProjectFileContents;
+      }
+      const config = readYamlFromString(contents) as Metadata;
       const projFormats = formatKeys(config);
       if (ld.isEqual(formats, projFormats)) {
         return index;

src/project/types/project-default.ts

@@ -12,6 +12,8 @@ import { kJupyterEngine } from "../../execute/types.ts";
 
 import { ProjectCreate, ProjectScaffoldFile, ProjectType } from "./types.ts";
 
+export const kDefaultProjectFileContents = "{ project: { type: 'default' } }";
+
 export const defaultProjectType: ProjectType = {
   type: "default",