Re-allow users to not select an emulator UI port.

Fixes #8621

Sorry; somehow I missed that there was a case where numbers are not required.
Keeps the library's behavior of assuming that numbers are required, but allows
explicitly overwriting this with a "reququired: false". This is the only
value that can be provided to "required". Using type magic, the return type
of number can only be defined if "required: false" is passed in.

Author: inlined

src/init/features/emulators.ts

@@ -81,13 +81,10 @@ export async function doSetup(setup: Setup, config: Config) {
       });
 
       if (ui.enabled) {
-        ui.port = await number(
-          `Which port do you want to use for the ${clc.underline(uiDesc)} (leave empty to use any available port)?`,
-        );
-
-        // Parse the input as a number
-        const portNum = Number.parseInt(ui.port as any);
-        ui.port = isNaN(portNum) ? undefined : portNum;
+        ui.port = await number({
+          message: `Which port do you want to use for the ${clc.underline(uiDesc)} (leave empty to use any available port)?`,
+          required: false,
+        });
       }
     }
 

src/prompt.ts

@@ -214,7 +214,12 @@ export async function number(message: string): Promise<number>;
  */
 export async function number(opts: NumberOptions): Promise<number>;
 
-export async function number(opts: string | NumberOptions): Promise<number> {
+/**
+ * Prompt a user for an optional number.
+ */
+export async function number(opts: NumberOptions & { required: false }): Promise<number | undefined>;
+
+export async function number(opts: string | NumberOptions): Promise<number | undefined> {
   if (typeof opts === "string") {
     opts = { message: opts };
   } else {
@@ -224,7 +229,7 @@ export async function number(opts: string | NumberOptions): Promise<number> {
     }
   }
 
-  return (await inquirer.number({ ...opts, required: true }))!;
+  return await inquirer.number({ required: true, ...opts });
 }
 
 /**