[p5.js 2.0+ Bug Report]: loadTable() drops the last row of a one-column CSV without a trailing newline #9222

Most appropriate sub-area of p5.js?

• Accessibility
• Color
• Core/Environment/Rendering
• Data
• DOM
• Events
• Image
• IO
• Math
• Typography
• Utilities
• WebGL
• WebGPU
• p5.strands
• Build process
• Unit testing
• Internationalization
• Friendly errors
• Other (specify if possible)

p5.js version

2.3.4 (also on main)

Web browser and version

Chrome 153

Operating system

Linux

Steps to reproduce this

loadTable() drops the last row of a one-column CSV that doesn't end with a newline. If the file is a single value, it throws instead.

With names.csv containing alice\nbob\ncarol (no newline at the end):

async function setup() {
  noCanvas();
  const t = await loadTable('names.csv');
  print(t.getRowCount()); // 2, expected 3
  print(t.getArray());    // [["alice"], ["bob"]]
}

• alice\nbob\ncarol\n (with a trailing newline) gives 3 rows, as expected.
• A file containing just 42 throws Cannot read properties of undefined (reading 'length'). FES then reports "there was a problem loading your table file. Try checking if the file path is correct", which sends people looking at the wrong thing.
• Multi-column files aren't affected: x,y\n1,2 parses fine without a trailing newline.

The cause is in src/io/csv.js, at the end of parse():

// flush the last value
if (ctx.entry.length !== 0) {
  valueEnd(ctx);
  entryEnd(ctx);
}

ctx.entry only gets a value when a separator or newline ends it. In a one-column row, the last value is still sitting in ctx.value with ctx.entry empty, so the flush is skipped. parse('a\nb') returns [["a"]], parse('only') and parse('"only"') return [], and parse('a\n\nb') loses the b. For the single-value file, loadTable then does data[0].length on an empty array.

I think the fix is to flush whenever the parser is partway through a value, i.e. if (state !== 0 || ctx.entry.length !== 0). State 2 covers an unquoted value and 4 covers a closed quote. A trailing newline leaves state 0 with an empty entry, so it still doesn't add a phantom row. A separate guard in loadTable for an empty file (data[0] undefined) would make that case return an empty table instead of throwing. I'm happy to open a PR with both and unit tests for parse if this sounds right.