Use null across EH boundary instead of undefined

src/vs/workbench/api/browser/mainThreadWorkspace.ts

@@ -24,6 +24,7 @@ import { ExtHostContext, ExtHostWorkspaceShape, IExtHostContext, MainContext, Ma
 import { IEnvironmentService } from 'vs/platform/environment/common/environment';
 import { isEqualOrParent } from 'vs/base/common/resources';
 import { INotificationService } from 'vs/platform/notification/common/notification';
+import { withNullAsUndefined } from 'vs/base/common/types';
 
 @extHostNamedCustomer(MainContext.MainThreadWorkspace)
 export class MainThreadWorkspace implements MainThreadWorkspaceShape {
@@ -122,21 +123,21 @@ export class MainThreadWorkspace implements MainThreadWorkspaceShape {
 
 	// --- search ---
 
-	$startFileSearch(includePattern: string, _includeFolder: UriComponents | undefined, excludePatternOrDisregardExcludes: string | false | undefined, maxResults: number, token: CancellationToken): Promise<URI[] | undefined> {
+	$startFileSearch(includePattern: string | null, _includeFolder: UriComponents | null, excludePatternOrDisregardExcludes: string | false | null, maxResults: number | null, token: CancellationToken): Promise<UriComponents[] | null> {
 		const includeFolder = URI.revive(_includeFolder);
 		const workspace = this._contextService.getWorkspace();
 		if (!workspace.folders.length) {
-			return Promise.resolve(undefined);
+			return Promise.resolve(null);
 		}
 
 		const query = this._queryBuilder.file(
 			includeFolder ? [includeFolder] : workspace.folders.map(f => f.uri),
 			{
-				maxResults,
+				maxResults: withNullAsUndefined(maxResults),
 				disregardExcludeSettings: (excludePatternOrDisregardExcludes === false) || undefined,
 				disregardSearchExcludeSettings: true,
 				disregardIgnoreFiles: true,
-				includePattern,
+				includePattern: withNullAsUndefined(includePattern),
 				excludePattern: typeof excludePatternOrDisregardExcludes === 'string' ? excludePatternOrDisregardExcludes : undefined,
 				_reason: 'startFileSearch'
 			});

src/vs/workbench/api/common/extHost.protocol.ts

@@ -579,7 +579,7 @@ export interface ITextSearchComplete {
 }
 
 export interface MainThreadWorkspaceShape extends IDisposable {
-	$startFileSearch(includePattern: string | undefined, includeFolder: UriComponents | undefined, excludePatternOrDisregardExcludes: string | false | undefined, maxResults: number | undefined, token: CancellationToken): Promise<UriComponents[] | undefined>;
+	$startFileSearch(includePattern: string | null, includeFolder: UriComponents | null, excludePatternOrDisregardExcludes: string | false | null, maxResults: number | null, token: CancellationToken): Promise<UriComponents[] | null>;
 	$startTextSearch(query: search.IPatternInfo, options: ITextQueryBuilderOptions, requestId: number, token: CancellationToken): Promise<ITextSearchComplete>;
 	$checkExists(folders: UriComponents[], includes: string[], token: CancellationToken): Promise<boolean>;
 	$saveAll(includeUntitled?: boolean): Promise<boolean>;

src/vs/workbench/api/common/extHostWorkspace.ts

@@ -24,6 +24,7 @@ import { ExtHostWorkspaceShape, IWorkspaceData, MainThreadMessageServiceShape, M
 import { ExtensionIdentifier, IExtensionDescription } from 'vs/platform/extensions/common/extensions';
 import { Barrier } from 'vs/base/common/async';
 import { Schemas } from 'vs/base/common/network';
+import { withUndefinedAsNull } from 'vs/base/common/types';
 
 export interface IExtHostWorkspaceProvider {
 	getWorkspaceFolder2(uri: vscode.Uri, resolveParent?: boolean): Promise<vscode.WorkspaceFolder | undefined>;
@@ -438,7 +439,13 @@ export class ExtHostWorkspace implements ExtHostWorkspaceShape, IExtHostWorkspac
 			return Promise.resolve([]);
 		}
 
-		return this._proxy.$startFileSearch(includePattern, includeFolder, excludePatternOrDisregardExcludes, maxResults, token)
+		return this._proxy.$startFileSearch(
+			withUndefinedAsNull(includePattern),
+			withUndefinedAsNull(includeFolder),
+			withUndefinedAsNull(excludePatternOrDisregardExcludes),
+			withUndefinedAsNull(maxResults),
+			token
+		)
 			.then(data => Array.isArray(data) ? data.map(d => URI.revive(d)) : []);
 	}