fix(@angular/cli): improve error logging when resolving update migrations

Failure to resolve a migration package from the workspace root will now not crash and instead error with a message.  Verbose logging (`--verbose`) is also added to provide more details regarding the resolution process.

(cherry picked from commit 9a44bf4)

Author: clydin

packages/angular/cli/commands/update-impl.ts

@@ -284,6 +284,12 @@ export class UpdateCommand extends Command<UpdateCommandSchema> {
       );
     }
 
+    const logVerbose = (message: string) => {
+      if (options.verbose) {
+        this.logger.info(message);
+      }
+    };
+
     if (options.all) {
       const updateCmd = this.packageManager === PackageManager.Yarn
         ? `'yarn upgrade-interactive' or 'yarn upgrade'`
@@ -654,7 +660,28 @@ export class UpdateCommand extends Command<UpdateCommandSchema> {
       for (const migration of migrations) {
         // Resolve the package from the workspace root, as otherwise it will be resolved from the temp
         // installed CLI version.
-        const packagePath = require.resolve(migration.package, { paths: [this.context.root] });
+        let packagePath;
+        logVerbose(
+          `Resolving migration package '${migration.package}' from '${this.context.root}'...`,
+        );
+        try {
+          packagePath = require.resolve(migration.package, { paths: [this.context.root] });
+        } catch (e) {
+          if (e.code === 'MODULE_NOT_FOUND') {
+            logVerbose(e.toString());
+            this.logger.error(
+              `Migrations for package (${migration.package}) were not found.` +
+                ' The package could not be found in the workspace.',
+            );
+          } else {
+            this.logger.error(
+              `Unable to resolve migrations for package (${migration.package}).  [${e.message}]`,
+            );
+          }
+
+          return 1;
+        }
+
         let migrations;
 
         // Check if it is a package-local location