Fix the lint check for promises nobody awaits

A Node.js webhook handler charges a customer, then records the charge. Its line chargeCustomer(customerId, amount); // returns a Promise has no await. So a failed charge never reaches the try/catch, and the row still says ok. The team wants a lint check for floating promises: calls to an async function whose promise nobody awaits, chains or returns.

An assistant wrote find_floating_promises(body_lines, async_functions). It is in the editor. It has a bug. Find it and fix it.

Input and output:

• body_lines: the lines of a function body, in order. A line can have spaces or tabs at either end. The list can be empty.
• async_functions: the names of the functions that return a promise, such as "chargeCustomer" or "db.insert". Ignore an empty name. The list can be empty.
• Return the numbers of the lines that hold a floating promise, as a list of integers.

Rules the tests check:

• Lines are numbered from 1, and every line counts, blank ones and comments included.
• Trim spaces and tabs at both ends of each line. Every check below reads the whole trimmed line, including any comment at its end and any text in quotes.
• Skip a line that is empty after trimming or that starts with //. Only a line that starts with // is a comment. Code before a // still counts.
• A line calls a name when the name appears in it followed directly by (. The character just before the name must not be a letter (a to z or A to Z), a digit, _ or $. A name at the start of the line has no character before it, so it counts. One such place in the line is enough.
• So recharge( does not call charge, but x.charge( does. charge ( with a space does not.
• Names are case sensitive.
• Skip a line that calls none of the names.
• A line that calls a name is still fine in any of these cases:
  • It contains the text await anywhere, even inside a longer word or a comment.
  • It contains .then( or .catch( anywhere.
  • It starts with return followed by a space.
• Every other line that calls a name holds a floating promise. Add its number once, even when it calls several names.
• Return the line numbers in ascending order. Return an empty list when no line is flagged.