cherrypick(release-1.4): throw unexpected platform error upon call (#3946)

Cherry-pick:
- PR #3943 SHA 0090cd943c8c724cb0fe8b02f4fd7f7e7ba837bd

References #3919 and #3935

Co-authored-by: Pavel Feldman <[email protected]>

Author: aslushnikov

src/client/browserType.ts

@@ -54,6 +54,8 @@ export class BrowserType extends ChannelOwner<channels.BrowserTypeChannel, chann
   }
 
   executablePath(): string {
+    if (!this._initializer.executablePath)
+      throw new Error('Browser is not supported on current platform');
     return this._initializer.executablePath;
   }
 

src/server/browserType.ts

@@ -47,7 +47,7 @@ type WebSocketNotPipe = { webSocketRegex: RegExp, stream: 'stdout' | 'stderr' };
 
 export abstract class BrowserTypeBase implements BrowserType {
   private _name: string;
-  private _executablePath: string | undefined;
+  private _executablePath: string;
   private _webSocketNotPipe: WebSocketNotPipe | null;
   private _browserDescriptor: browserPaths.BrowserDescriptor;
   readonly _browserPath: string;
@@ -57,13 +57,11 @@ export abstract class BrowserTypeBase implements BrowserType {
     const browsersPath = browserPaths.browsersPath(packagePath);
     this._browserDescriptor = browser;
     this._browserPath = browserPaths.browserDirectory(browsersPath, browser);
-    this._executablePath = browserPaths.executablePath(this._browserPath, browser);
+    this._executablePath = browserPaths.executablePath(this._browserPath, browser) || '';
     this._webSocketNotPipe = webSocketOrPipe;
   }
 
   executablePath(): string {
-    if (!this._executablePath)
-      throw new Error('Browser is not supported on current platform');
     return this._executablePath;
   }