[Fix] Sideloaded games on Windows (#3562)

* Support empty commandParts in callRunner's Windows case

In case the array is empty, we have to make sure to not pass the parameter at
all (otherwise PS will error out)

This is used by sideloaded games

* Correctly pass the "runner" path for sideloaded games

Sideloaded games pass their executable path as the runner. Before, this was done
 a little incorrectly. Assume the selected executable is
`C:\Windows\System32\cmd.exe`. Before, the runner would then be:
{
  bin: `C:\Windows\System32\cmd.exe`
  dir: `C:\Windows\System32\`
}

callRunner then just `join`s together these paths, resulting in
`C:\Windows\System32\C:\Windows\System32\cmd.exe`. This is obviously wrong and
will not work.

Now, we correctly pass just the bin for `bin` (`cmd.exe` in our example). This
is also in-line with how regular runners work

* Add "./" in callRunner directly

This was somewhat flawed before; callRunner relied on an implementation detail
of `splitPathAndName` (it adding "./" to the "bin"). The relevant code was now
moved to callRunner itself

src/backend/launcher.ts

@@ -993,6 +993,10 @@ async function callRunner(
   let bin = runner.bin
   let fullRunnerPath = join(runner.dir, bin)
 
+  // macOS/Linux: `spawn`ing an executable in the current working directory
+  // requires a "./"
+  if (!isWindows) bin = './' + bin
+
   // On Windows: Use PowerShell's `Start-Process` to wait for the process and
   // its children to exit, provided PowerShell is available
   if (shouldUsePowerShell === null)
@@ -1005,10 +1009,10 @@ async function callRunner(
       'Start-Process',
       `"\`"${fullRunnerPath}\`""`,
       '-Wait',
-      '-ArgumentList',
-      argsAsString,
       '-NoNewWindow'
     ]
+    if (argsAsString) commandParts.push('-ArgumentList', argsAsString)
+
     bin = fullRunnerPath = 'powershell'
   }
 

src/backend/storeManagers/storeManagerCommon/games.ts

@@ -8,7 +8,7 @@ import {
   LogPrefix,
   logWarning
 } from '../../logger/logger'
-import { dirname } from 'path'
+import { basename, dirname } from 'path'
 import { constants as FS_CONSTANTS } from 'graceful-fs'
 import i18next from 'i18next'
 import {
@@ -220,7 +220,7 @@ export async function launchGame(
         {
           name: runner,
           logPrefix: LogPrefix.Backend,
-          bin: executable,
+          bin: basename(executable),
           dir: dirname(executable)
         },
         {

src/backend/utils.ts

@@ -428,12 +428,7 @@ function showItemInFolder(item: string) {
 
 function splitPathAndName(fullPath: string): { dir: string; bin: string } {
   const dir = dirname(fullPath)
-  let bin = basename(fullPath)
-  // On Windows, you can just launch executables that are in the current working directory
-  // On Linux, you have to add a ./
-  if (!isWindows) {
-    bin = './' + bin
-  }
+  const bin = basename(fullPath)
   // Make sure to always return this as `dir, bin` to not break path
   // resolution when using `join(...Object.values(...))`
   return { dir, bin }