refactor: utilize type narrowing (#33075)

PR Close #33075

packages/compiler-cli/src/diagnostics/typescript_symbols.ts

@@ -624,7 +624,7 @@ function findClassSymbolInContext(type: StaticSymbol, context: TypeContext): ts.
     // This handles a case where an <packageName>/index.d.ts and a <packageName>/<packageName>.d.ts
     // are in the same directory. If we are looking for <packageName>/<packageName> and didn't
     // find it, look for <packageName>/index.d.ts as the program might have found that instead.
-    const p = type.filePath as string;
+    const p = type.filePath;
     const m = p.match(INDEX_PATTERN);
     if (m) {
       const indexVersion = path.join(path.dirname(p), 'index.d.ts');

packages/compiler-cli/src/metadata/evaluator.ts

@@ -306,7 +306,7 @@ export class Evaluator {
                 error = propertyValue;
                 return true;  // Stop the forEachChild.
               } else {
-                obj[<string>propertyName] = isPropertyAssignment(assignment) ?
+                obj[propertyName] = isPropertyAssignment(assignment) ?
                     recordEntry(propertyValue, assignment.initializer) :
                     propertyValue;
               }
@@ -401,7 +401,7 @@ export class Evaluator {
           return recordEntry(member, node);
         }
         if (expression && this.isFoldable(propertyAccessExpression.expression))
-          return (<any>expression)[<string>member];
+          return (<any>expression)[member];
         if (isMetadataModuleReferenceExpression(expression)) {
           // A select into a module reference and be converted into a reference to the symbol
           // in the module

packages/compiler-cli/src/ngtsc/annotations/src/directive.ts

@@ -271,7 +271,7 @@ export function extractQueryMetadata(
   } else if (typeof arg === 'string') {
     predicate = [arg];
   } else if (isStringArrayOrDie(arg, '@' + name)) {
-    predicate = arg as string[];
+    predicate = arg;
   } else {
     throw new FatalDiagnosticError(
         ErrorCode.VALUE_HAS_WRONG_TYPE, node, `@${name} predicate cannot be interpreted`);