[wasm][debugger] Fix exceptions on eval

[ilonatommy]

Fixes #61665.

• Added a mechanism that allows us to show some exceptions (of ReturnAsErrorException type) to users.
• Divided exceptions on script evaluation into 2 categories: thrown by user's error inside the script (compilation error) and all the other exceptions that should be hidden and are for our info only.
• Removes IsErr property from result. Now only IsOk can be used to determine if Result has error or not.

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Issue Details

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• Added a mechanism that allows us to show some exceptions (of ReturnAsErrorException type) to users.
• Divided exceptions on script evaluation into 2 categories: thrown by user's error inside the script (compilation error) and all the other exceptions that should be hidden and are for our info only.

Author:	ilonatommy
Assignees:	ilonatommy
Labels:	arch-wasm, area-Debugger-mono
Milestone:	-

[lewing]

A couple of issues. I think we might want to see if we can clean up the error result handling a bit too.

[radical]

Can you share how it looks different in practice?

1. how do the errors show up now, compared to earlier? For the user, and in the log
2. How does the stack trace show up for the user?

[ilonatommy]

Can you share how it looks different in practice?

1. how do the errors show up now, compared to earlier?
   a) For the user:

Sure. So before there was no exception information shown, here we break and evaluate non-existing-variable variable that does not exist and we got nothing after hovering over the text.

How it looks like now - evaluation of non existing variable + hovering over results in showing a window with exception details:

This PR has no effect on user defined exceptions.

b) and in the log:

all exceptions that are shown for the user are not logged anymore, so if we evaluate non exisiting variable on main we get

[11:08:51] fail: Microsoft.WebAssembly.Diagnostics.DevToolsProxy[0] sending error response for id: msg-:::105 -> [Result: IsOk: False, IsErr: True, Value: , Error: {   "result": {     "type": "object",     "subtype": "error",     "description": "The name non does not exist in the current context",     "className": "ReferenceError"   } } ]

but on this PR we don't get any log entry.

2. How does the stack trace show up for the user?

No change as well,

Internally thrown errors, e.g. evaluation of currentCount ~= 0 on the breakpoint from screenshot above is not shown to the user as it is recognized as AssignmentExpressionSyntax and throws Exception("Assignment not implemented") and logged as:

[11:40:43] fail: Microsoft.WebAssembly.Diagnostics.DevToolsProxy[0] sending error response for id: msg-:::123 -> [Result: IsOk: False, IsErr: True, Value: , Error: {   "message": "Assignment is not implemented yet" } ]

However, when we evaluate currentCount ~^ 0 that is not treated as assignment and the debugger is trying to compile it we are getting a detailed info why the compilation failed:

with nothing new in the log. Before we only got not available info that did not tell much to the user.

[radical]

This doesn't look right. We now have a resultOrError, and error, but also isError. Why do we need all 3?

[ilonatommy]

Actually I left it only because of the FromJson function:

        public static Result FromJson(JObject obj)
        {
            //Log ("protocol", $"from result: {obj}");
            return new Result(obj["result"] as JObject, false, obj["error"] as JObject);
        }

that I did not want to change but now I did it and the version with 2 arguments works equally good. Thanks!