fix(@schematics/angular): remove solution style throw an error

remove-solution-style-tsconfig migration fail when upgrading from version 10.0.* to 10.1.* with the following error:
[error] Error: Could not read 'tsconfig.json'

Author: eranshmil

packages/schematics/angular/migrations/update-10/remove-solution-style-tsconfig.ts

@@ -35,11 +35,16 @@ export default function (): Rule {
   return (host, context) => {
     const logger = context.logger;
 
-    const files = new JSONFile(host, 'tsconfig.json').get(['files']);
-    if (!(Array.isArray(files) && files.length === 0)) {
-      logger.info('Migration has already been executed.');
+    try {
+      const files = new JSONFile(host, 'tsconfig.json').get(['files']);
 
-      return;
+      if (!(Array.isArray(files) && files.length === 0)) {
+        logger.info('Migration has already been executed.');
+
+        return;
+      }
+    } catch {
+      host.create('tsconfig.json', '');
     }
 
     if (host.exists('tsconfig.base.json')) {

packages/schematics/angular/migrations/update-10/remove-solution-style-tsconfig_spec.ts

@@ -70,7 +70,6 @@ describe('Migration to remove "Solution Style" tsconfig', () => {
 
     // Create tsconfigs
     const compilerOptions = { target: 'es2015' };
-    createJsonFile(tree, 'tsconfig.json', { files: [] });
     createJsonFile(tree, 'tsconfig.base.json', { compilerOptions });
     createJsonFile(tree, 'tsconfig.common.json', { compilerOptions });
     createJsonFile(tree, 'src/tsconfig.json', { extends: './../tsconfig.base.json', compilerOptions });
@@ -82,9 +81,13 @@ describe('Migration to remove "Solution Style" tsconfig', () => {
   });
 
   it(`should rename 'tsconfig.base.json' to 'tsconfig.json'`, async () => {
+    const logs: string[] = [];
+    schematicRunner.logger.subscribe((m) => logs.push(m.message));
+
     const newTree = await schematicRunner.runSchematicAsync(schematicName, {}, tree).toPromise();
     expect(readJsonFile(newTree, 'tsconfig.json')['compilerOptions']).toBeTruthy();
     expect(newTree.exists('tsconfig.base.json')).toBeFalse();
+    expect(logs.join('\n')).toEqual('');
   });
 
   it(`should update extends from 'tsconfig.base.json' to 'tsconfig.json'`, async () => {