Improve error message when functions:shell command fails due to missi…

…ng project association. (#6088)

**Before**:

```
$ firebase functions:shell
Error: An unexpected error has occurred.
```

**After**:

```
$  firebase functions:shell
Error: No currently active project.
To run this command, you need to specify a project. You have two options:
- Run this command with --project <alias_or_project_id>.
- Set an active project by running firebase use --add, then rerun this command.
To list all the Firebase projects to which you have access, run firebase projects:list.
To learn about active projects for the CLI, visit https://firebase.google.com/docs/cli#project_aliases
```

Fixes #6070

src/functionsShellCommandAction.ts

@@ -5,17 +5,18 @@ import * as _ from "lodash";
 import * as request from "request";
 import * as util from "util";
 
+import * as shell from "./emulator/functionsEmulatorShell";
+import * as commandUtils from "./emulator/commandUtils";
 import { FunctionsServer } from "./serve/functions";
 import LocalFunction from "./localFunction";
 import * as utils from "./utils";
 import { logger } from "./logger";
-import * as shell from "./emulator/functionsEmulatorShell";
-import * as commandUtils from "./emulator/commandUtils";
 import { EMULATORS_SUPPORTED_BY_FUNCTIONS, EmulatorInfo, Emulators } from "./emulator/types";
 import { EmulatorHubClient } from "./emulator/hubClient";
 import { resolveHostAndAssignPorts } from "./emulator/portUtils";
 import { Options } from "./options";
 import { Constants } from "./emulator/constants";
+import { needProjectId } from "./projectUtils";
 
 const serveFunctions = new FunctionsServer();
 
@@ -29,8 +30,8 @@ export const actionFunction = async (options: Options) => {
     debugPort = commandUtils.parseInspectionPort(options);
   }
 
-  utils.assertDefined(options.project);
-  const hubClient = new EmulatorHubClient(options.project);
+  needProjectId(options);
+  const hubClient = new EmulatorHubClient(options.project!);
 
   let remoteEmulators: Record<string, EmulatorInfo> = {};
   if (hubClient.foundHub()) {

src/utils.ts

@@ -596,21 +596,6 @@ export function thirtyDaysFromNow(): Date {
   return new Date(Date.now() + THIRTY_DAYS_IN_MILLISECONDS);
 }
 
-/**
- * See:
- * https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-7.html#assertion-functions
- */
-export function assertDefined<T>(val: T, message?: string): asserts val is NonNullable<T> {
-  if (val === undefined || val === null) {
-    throw new AssertionError({
-      message: message || `expected value to be defined but got "${val}"`,
-    });
-  }
-}
-
-/**
- *
- */
 export function assertIsString(val: any, message?: string): asserts val is string {
   if (typeof val !== "string") {
     throw new AssertionError({
@@ -619,9 +604,6 @@ export function assertIsString(val: any, message?: string): asserts val is strin
   }
 }
 
-/**
- *
- */
 export function assertIsNumber(val: any, message?: string): asserts val is number {
   if (typeof val !== "number") {
     throw new AssertionError({
@@ -630,9 +612,6 @@ export function assertIsNumber(val: any, message?: string): asserts val is numbe
   }
 }
 
-/**
- *
- */
 export function assertIsStringOrUndefined(
   val: any,
   message?: string