Standardize SDK init errors #324
Description
Error handling and onError calls during SDK initialization (flagsmith.init()) are currently inconsistent. Some are plain Error objects, others are raw strings unparsed HTML responses.
E.g
<!DOCTYPE html>
...
<title>Error</title>
...
<pre>Cannot POST /test/identities/</pre>
...
Standardize the errors, by having a FlagsmithError subclass for example would help handling them in a more programmatic way.
DoD
- Each path in init throws its own specific error
- A new section in the javascript client documentation describes all the possible errors
- For each Flagsmith error, the tests should be able to confirm the error is caught, thrown and formatted as described per the decoumentation
- If a critical error happens,
client.initialisedshould be false