`executeCode()` API should store pending code, run `code`, and then put pending code back

[gadenbuie]

System details:

Positron and OS details:

Positron Version: 2025.02.0 (Universal) build 171
Code - OSS Version: 1.96.0
Commit: 55f7331
Date: 2025-02-10T16:03:19.797Z
Electron: 32.2.6
Chromium: 128.0.6613.186
Node.js: 20.18.1
V8: 12.8.374.38-electron.0
OS: Darwin arm64 24.3.0

Interpreter details:

R 4.4.2

Describe the issue:

Running the R: Load R package command places devtools::load_all() into the console, appending it next to whatever code is currently in the console.

Steps to reproduce the issue:

1. Open a project containing an R package
2. Write, but do not submit, the following code in the Console stop("bad robot")
3. Run the "R: Load R Package" command
4. Both the stop() call and devtools::load_all() call will be evaluated. The package will not load because of the error from the stop() call.

A similar problem occurs if you have invalid R code in the Console.

Expected or desired behavior:

The stop("bad robot") code should remain in the console, un-submitted, but the devtools::load_all() is evaluated in the console.

(FWIW, this is the behavior in RStudio.)

Were there any error messages in the UI, Output panel, or Developer Tools console?

[juliasilge]

Right now, this command just provides a bit of code:

positron/extensions/positron-r/src/commands.ts

Line 62 in ef59db8

executeCodeForCommand('devtools', 'devtools::load_all()');

And then that goes to the Positron API here:

positron/extensions/positron-r/src/commands.ts

Line 324 in ef59db8

positron.runtime.executeCode('r', code, true);

I don't believe that right now we have a way to say something like, "first store the pending code, then execute this new bit of code, and now get the original pending code back again".

[DavisVaughan]

This is actually a regression, I've tracked it back to being introduced in 2025.02.0 (Universal) build 94 (Jan 23) and my current guess is that it was by #6064

@hadley and I hit this a lot, so we should prioritize it before RC.

I'll use Cmd+Shift+L while in an R package to demonstrate this. It sends devtools::load_all() to the Console.

Here is behavior before this release, notice how 1+1 is preserved and not executed:

Screen.Recording.2025-05-14.at.11.57.38.AM.mov

Here is behavior after this release (on main right now), notice how 1+1 is inadvertently executed:

Screen.Recording.2025-05-14.at.11.59.09.AM.mov