Improve error message when EJS execution fails

[cscheid]

See https://github.com/beyond2060/quarto-bug-reproduction for a minimal example.

[cderv]

For more context the error traceback is

❯ quarto render index.qmd
ERROR: TypeError: Cannot read properties of undefined (reading 'split')

Stack trace:
    at eval (eval at <anonymous> (https://cdn.skypack.dev/-/[email protected]/dist=es2019,mode=imports/unoptimized/template.js:58:12), <anonymous>:23:22)
    at renderEjs (file:///C:/Users/chris/Documents/DEV_R/quarto-cli/src/core/ejs.ts:39:16)
    at templateMarkdownHandler (file:///C:/Users/chris/Documents/DEV_R/quarto-cli/src/project/types/website/listing/website-listing-template.ts:183:26)
    at markdownHandler (file:///C:/Users/chris/Documents/DEV_R/quarto-cli/src/project/types/website/listing/website-listing.ts:352:14)
    at file:///C:/Users/chris/Documents/DEV_R/quarto-cli/src/project/types/website/listing/website-listing.ts:179:7
    at Array.forEach (<anonymous>)
    at listingHtmlDependencies (file:///C:/Users/chris/Documents/DEV_R/quarto-cli/src/project/types/website/listing/website-listing.ts:177:22)
    at eventLoopTick (ext:core/01_core.js:175:7)
    at async Object.formatExtras (file:///C:/Users/chris/Documents/DEV_R/quarto-cli/src/project/types/website/website.ts:235:39)
    at async runPandoc (file:///C:/Users/chris/Documents/DEV_R/quarto-cli/src/command/render/pandoc.ts:392:10)

And it happens because

• A post does not have a title
• The custom EJS is doing

   <a href="<%- item.path %>" class="title listing-title" data-original-href="<%- item.path %>"><%= item.title.split('*').join('') %></a>

item.title being undefined, it throws an error. Though it requires investigation to understand what and where.

[cscheid]

We should be catching any exception there, though, and reporting the file where this fails to the user.