fix(@angular/cli): only show add/update package install output on errors

Closes angular#16014
Closes angular#16027

Author: clydin

packages/angular/cli/tasks/install-package.ts

@@ -8,12 +8,7 @@
 
 import { logging } from '@angular-devkit/core';
 import { spawnSync } from 'child_process';
-import {
-  existsSync,
-  mkdtempSync,
-  readFileSync,
-  realpathSync,
-} from 'fs';
+import { existsSync, mkdtempSync, readFileSync, realpathSync } from 'fs';
 import { tmpdir } from 'os';
 import { join, resolve } from 'path';
 import * as rimraf from 'rimraf';
@@ -45,21 +40,26 @@ export function installPackage(
 
   logger.info(colors.green(`Installing packages for tooling via ${packageManager}.`));
 
-  const { status } = spawnSync(
+  const { status, stderr } = spawnSync(
     packageManager,
     [
       ...installArgs,
       ...extraArgs,
     ],
     {
-      stdio: 'inherit',
+      stdio: 'pipe',
+      encoding: 'utf8',
       shell: true,
       cwd,
     },
   );
 
   if (status !== 0) {
-    throw new Error('Package install failed, see above.');
+    let errors = stderr.trim();
+    if (errors.length) {
+      errors += '\n';
+    }
+    throw new Error(errors + `Package install failed${errors.length ? ', see above' : ''}.`);
   }
 
   logger.info(colors.green(`Installed packages for tooling via ${packageManager}.`));
@@ -76,7 +76,7 @@ export function installTempPackage(
   process.on('exit', () => {
     try {
       rimraf.sync(tempPath);
-    } catch { }
+    } catch {}
   });
 
   // setup prefix/global modules path
@@ -132,10 +132,7 @@ export function runTempPackageBin(
     throw new Error(`Cannot locate bin for temporary package: ${packageNameNoVersion}.`);
   }
 
-  const argv = [
-    binPath,
-    ...args,
-  ];
+  const argv = [binPath, ...args];
 
   const { status, error } = spawnSync('node', argv, {
     stdio: 'inherit',