Base prefix before a simple expansion, $((10#$n)), produces an ERROR node #351

Thanks for tree-sitter-bash, and for keeping it maintained!

A base prefix followed by a simple (unbraced) expansion inside arithmetic produces an ERROR node:

echo $((10#$n))

Actual tree (at a06c2e4415e9):

(program (command name: (command_name (word))
  argument: (arithmetic_expansion (ERROR) (simple_expansion (variable_name)))))

The braced form and a literal both parse clean:

• echo $((10#${n})) gives (arithmetic_expansion (number (expansion (variable_name))))
• echo $((10#5)) gives (arithmetic_expansion (number))

Expected: 10#$n should be a number wrapping a simple_expansion, the same way the braced form wraps an expansion:

(arithmetic_expansion (number (simple_expansion (variable_name))))

$((10#$n)) is the standard idiom for making bash read a zero-padded value (08, 09) as decimal, so it turns up often in date and version handling.

Found while indexing with codebase-memory-mcp (DeusData/codebase-memory-mcp#2078).