Fix installation on windows

Author: hasufell

src/hlsBinaries.ts

@@ -164,7 +164,7 @@ export async function downloadHaskellLanguageServer(
         wrapper = downloadedWrapper;
     }
 
-    const ghcup = path.join(storagePath, 'ghcup');
+    const ghcup = path.join(storagePath, `ghcup${exeExt}`);
     const updateBehaviour = workspace.getConfiguration('haskell').get('updateBehavior') as UpdateBehaviour;
     const [installable_hls, latest_hls_version, project_ghc] = await getLatestSuitableHLS(
         context,
@@ -294,7 +294,7 @@ async function getLatestSuitableHLS(
     // TODO: we may run this function twice on startup (e.g. in extension.ts)
     const project_ghc =
         wrapper == undefined
-            ? await callAsync('ghc', ['--numeric-version'], storagePath, logger, undefined, false)
+            ? await callAsync(`ghc${exeExt}`, ['--numeric-version'], storagePath, logger, undefined, false)
             : await getProjectGHCVersion(wrapper, workingDir, logger);
 
     // get installable HLS that supports the project GHC version (this might not be the most recent)
@@ -371,9 +371,9 @@ export async function downloadGHCup(context: ExtensionContext, logger: Logger):
         fs.mkdirSync(storagePath);
     }
 
-    const ghcup = path.join(storagePath, 'ghcup');
+    const ghcup = path.join(storagePath, `ghcup${exeExt}`);
     // ghcup exists, just upgrade
-    if (fs.existsSync(path.join(storagePath, 'ghcup'))) {
+    if (fs.existsSync(ghcup)) {
         const args = ['--no-verbose', 'upgrade', '-i'];
         await callAsync(ghcup, args, storagePath, logger, undefined, false, { GHCUP_INSTALL_BASE_PREFIX: storagePath });
     } else {