fix(cdk/schematics): avoid throwing an error for empty program (#27060)

Fixes that the `ng update` schematics were throwing an error if the tsconfig doesn't match any files.

Fixes #27055.

src/cdk/schematics/update-tool/utils/parse-tsconfig.ts

@@ -12,6 +12,9 @@ import {FileSystemHost} from './virtual-host';
 import {dirname} from 'path';
 import {formatDiagnostics} from './diagnostics';
 
+/** Code of the error raised by TypeScript when a tsconfig doesn't match any files. */
+const NO_INPUTS_ERROR_CODE = 18003;
+
 /** Class capturing a tsconfig parse error. */
 export class TsconfigParseError extends Error {}
 
@@ -45,8 +48,12 @@ export function parseTsconfigFile(
     {},
   );
 
-  if (parsed.errors.length) {
-    throw new TsconfigParseError(formatDiagnostics(parsed.errors, fileSystem));
+  // Skip the "No inputs found..." error since we don't want to interrupt the migration if a
+  // tsconfig doesn't match a file. This will result in an empty `Program` which is still valid.
+  const errors = parsed.errors.filter(diag => diag.code !== NO_INPUTS_ERROR_CODE);
+
+  if (errors.length) {
+    throw new TsconfigParseError(formatDiagnostics(errors, fileSystem));
   }
 
   return parsed;