Fetch error handling is incorrect

[F. Levi]

In the code below we're assuming that if response.json() throws an error, it means we have a communication error. This is incorrect, it will only throw if the request body isn't valid JSON (https://fetch.spec.whatwg.org/#dom-body-json). As long as we can be 100% sure that Meilisearch client will only respond with a valid JSON error body text, this will never throw. If that isn't the case, maybe we should instead use response.text().

meilisearch-js/src/errors/http-error-handler.ts

Lines 5 to 26 in cd61a8c

 async function httpResponseErrorHandler(response: Response): Promise<Response> { 
   if (!response.ok) { 
     let responseBody 
     try { 
       // If it is not possible to parse the return body it means there is none 
       // In which case it is a communication error with the Meilisearch instance 
       responseBody = await response.json() 
     } catch (e: any) { 
       // Not sure on how to test this part of the code. 
       throw new MeiliSearchCommunicationError( 
         response.statusText, 
         response, 
         response.url 
       ) 
     } 
     // If the body is parsable, then it means Meilisearch returned a body with 
     // information on the error. 
     throw new MeiliSearchApiError(responseBody, response.status) 
   } 
  
   return response 
 } 

A communication error, or a network error would rather occur in the code below, before it gets to httpResponseErrorHandler, as described in the docs, and would be caught below and processed by httpErrorHandler.

A fetch() promise only rejects when the request fails, for example, because of a badly-formed request URL or a network error. A fetch() promise does not reject if the server responds with HTTP status codes that indicate errors (404, 504, etc.). Instead, a then() handler must check the Response.ok and/or Response.status properties.

meilisearch-js/src/http-requests.ts

Lines 165 to 174 in cd61a8c

   const response = await result.then((res: any) => 
     httpResponseErrorHandler(res) 
   ) 
   const parsedBody = await response.json().catch(() => undefined) 
  
   return parsedBody 
 } catch (e: any) { 
   const stack = e.stack 
   httpErrorHandler(e, stack, constructURL.toString()) 
 } 

Now, this httpErrorHandler messes with the error in such a way that information gets lost, which is another bug in itself, related to and detailed in #1612, and that's another issue that I should probably address separately.