Address PowerShell-related fuzz crashes (#463)

* Add item to fuzz corpus causing the crash

* Run Windows workflow on fuzz-related changes

* Update fuzz prep for PowerShell

Take carriage return into account when escaping backslashes at the end
of arguments.

.github/workflows/checks-windows.yml

@@ -3,9 +3,11 @@ on:
   pull_request:
     paths:
       - src/win.js
+      - test/fuzz/**
   push:
     paths:
       - src/win.js
+      - test/fuzz/**
     branches:
       - main
 

test/fuzz/_common.cjs

@@ -98,7 +98,7 @@ function getFuzzShell() {
 }
 
 /**
- * Prepare an argument for echoing to accomodate shell-specific behaviour.
+ * Prepare an argument for echoing to accommodate shell-specific behaviour.
  *
  * @param {object} args The function arguments.
  * @param {string} args.arg The input argument that will be echoed.
@@ -138,7 +138,7 @@ function prepareArg({ arg, quoted, shell }, disableExtraWindowsPreparations) {
 
         // ... and interprets arguments with `\"` as `"` (even if there's a null
         // character between `\` and `"`) so we escape the `\`.
-        arg = arg.replace(/(?<!\\)((?:\\\0*)+)(?="|$)/gu, "$1$1");
+        arg = arg.replace(/(?<!\\)((?:\\\0*)+)(?="|\r?$)/gu, "$1$1");
       } else {
         // ... interprets arguments with `\"` as `"` (even if there's a null
         // character between `\` and `"`) so we escape the `\`, except that the

test/fuzz/corpus/2099930321570f0517d3b7945c0506a9ec7b8dd588f5c9ff7e04ed1c53360ba5

@@ -0,0 +1 @@
+u�0 �\(?\