refactor(deploy): improve types to avoid extraneous runtime check (#7220)

* refactor: improve types to avoid extraneous runtime check

This code is messy, but by improving the typess and avoiding some reassignments we can let
TS understand it better and avoid an extraneous runtime check.

* refactor: use switch-case in deploy init choice

Author: serhalp

src/commands/deploy/deploy.ts

@@ -811,21 +811,21 @@ export const deploy = async (options: DeployOptionValues, command: BaseCommand)
 
   await command.authenticate(options.auth)
 
-  let siteId = site.id || options.site
-
   let initialSiteData: SiteInfo | undefined
   let newSiteData!: SiteInfo
-  if (siteId && !isEmpty(siteInfo)) {
+
+  const hasSiteData = (site.id || options.site) && !isEmpty(siteInfo)
+
+  if (hasSiteData) {
     initialSiteData = siteInfo
-    siteId = initialSiteData.id
   } else {
     log("This folder isn't linked to a site yet")
     const NEW_SITE = '+  Create & configure a new site'
     const EXISTING_SITE = 'Link this directory to an existing site'
 
-    const initializeOpts = [EXISTING_SITE, NEW_SITE]
+    const initializeOpts = [EXISTING_SITE, NEW_SITE] as const
 
-    const { initChoice } = await inquirer.prompt([
+    const { initChoice } = await inquirer.prompt<{ initChoice: typeof initializeOpts[number] }>([
       {
         type: 'list',
         name: 'initChoice',
@@ -834,25 +834,21 @@ export const deploy = async (options: DeployOptionValues, command: BaseCommand)
       },
     ])
     // create site or search for one
-    if (initChoice === NEW_SITE) {
-      newSiteData = await sitesCreate({}, command)
-      site.id = newSiteData.id
-      siteId = site.id
-    } else if (initChoice === EXISTING_SITE) {
-      newSiteData = await link({}, command)
-      site.id = newSiteData?.id
-      siteId = site.id
+    switch (initChoice) {
+      case NEW_SITE:
+        newSiteData = await sitesCreate({}, command)
+        site.id = newSiteData.id
+        break
+      case EXISTING_SITE:
+        newSiteData = await link({}, command)
+        site.id = newSiteData.id
+        break
     }
   }
 
-  if (!siteId) {
-    return logAndThrowError(
-      "Unable to determine which site to deploy to. Make sure you've run 'netlify link' or that you're specifying your desired site using the '--site' option.",
-    )
-  }
-
   // This is the best I could come up with to make TS happy with the complexities above.
   const siteData = initialSiteData ?? newSiteData
+  const siteId = siteData.id
 
   if (options.trigger) {
     return triggerDeploy({ api, options, siteData, siteId })