docs: make Request.failure return string by default (#5289)

docs/src/api/class-request.md

@@ -17,8 +17,7 @@ If request gets a 'redirect' response, the request is successfully finished with
 request is  issued to a redirected url.
 
 ## method: Request.failure
-- returns: <[null]|[Object]>
-  - `errorText` <[string]> Human-readable error message, e.g. `'net::ERR_FAILED'`.
+- returns: <[null]|[string]>
 
 The method returns `null` unless this request has failed, as reported by `requestfailed` event.
 

docs/src/api/javascript.md

@@ -2,6 +2,11 @@
 * langs: js
 - returns: <[null]|[Error]>
 
+## method: Request.failure
+* langs: js
+- returns: <[null]|[Object]>
+  - `errorText` <[string]> Human-readable error message, e.g. `'net::ERR_FAILED'`.
+
 ### param: ElementHandle.evalOnSelector.expression = %%-js-evalonselector-pagefunction-%%
 ### param: ElementHandle.evalOnSelectorAll.expression = %%-js-evalonselectorall-pagefunction-%%
 ### param: Frame.evalOnSelector.expression = %%-js-evalonselector-pagefunction-%%

docs/src/api/python.md

@@ -81,10 +81,6 @@ Path to the JavaScript file. If `path` is a relative path, then it is resolved r
 
 Raw script content.
 
-## method: Request.failure
-* langs: python
-- returns: <[null]|[string]>
-
 ## async method: Page.waitForEvent
 * langs: python
 - returns: <[EventContextManager]>