PR Checklist

• Addresses an existing open issue: fixes Docs: Playground gets into "cannot find source file" error state if started with blank file and config contents #11342
• That issue was marked as accepting prs
• Steps in Contributing were taken

Overview

Sorry, I didn’t consider that case either. @JoshuaKGoldberg

When fileType doesn't exist in the URL hash, the following hook is executed:

typescript-eslint/packages/website/src/components/editor/LoadedEditor.tsx

Lines 93 to 110 in db32b8a

	useEffect(() => {
	const newPath = `/input${fileType}`;
	if (tabs.code.uri.path !== newPath) {
	const code = tabs.code.getValue();
	const newModel = monaco.editor.createModel(
	code,
	undefined,
	monaco.Uri.file(newPath),
	);
	newModel.updateOptions({ insertSpaces: true, tabSize: 2 });
	if (tabs.code.isAttachedToEditor()) {
	editor.setModel(newModel);
	}
	tabs.code.dispose();
	tabs.code = newModel;
	system.writeFile(newPath, code);
	}
	}, [fileType, editor, system, monaco, tabs]);

As a result, system.write is called.

After that, this code runs.

typescript-eslint/packages/website/src/components/linter/createParser.ts

Lines 49 to 51 in db32b8a

	if (system.fileExists(filePath)) {
	compilerHost.updateFile(filePath, code);
	} else {

At this point, system has the file, but compilerHost does not.

At the result "cannot find source file" error occur in typescript-website

 updateFile: (fileName, content, optPrevTextSpan) => {
      const prevSourceFile = languageService.getProgram()!.getSourceFile(fileName)
      if (!prevSourceFile) {
        throw new Error("Did not find a source file for " + fileName)
      }