added null to possible return types for get method in url-search-params (#27183)

types/url-search-params/index.d.ts

@@ -9,7 +9,7 @@ declare class URLSearchParams {
     append(name: string, value: any): void;
     delete(name: string): void;
     entries(): Iterator<string>;
-    get(name: string): string;
+    get(name: string): string | null;
     getAll(name: string): string[];
     has(name: string): boolean;
     keys(): Iterator<string>;

types/url-search-params/url-search-params-tests.ts

@@ -11,6 +11,8 @@ params.entries();
 
 params.get("b");
 
+params.get("d");
+
 params.getAll("b");
 
 params.has("b");