Improve "Open in Editor" Error for Incorrect defaultEntrypoint

1 Describe the bug
2 When the "Open in Editor" feature needs to resolve a relative URL, it relies on the "Default Entrypoint" setting.
this setting is misconfigured, the file path resolution fails, but the resulting error message does not mention th
the "Default Entrypoint" setting could be the cause.
3
4 To Reproduce
5 Steps to reproduce the behavior:
6 1. Work with a project where source file URLs are relative (e.g., /main.js).
7 2. In the extension settings, provide an incorrect URL for "Default Entrypoint".
8 3. Launch the debugger and open the Edge DevTools.
9 4. In the DevTools, click a link to a relative source file.
10 5. See the error message.
11
12 Expected behavior
13 The error message should suggest that the user check both their pathMapping and their "Default Entrypoint" setti
when a file cannot be opened.
14
15 Current behavior
16 A generic error appears, stating: "Could not open '[sourcePath]' in the editor."
17
18 Additional context
19 Providing a more specific error message that mentions the "Default Entrypoint" setting would make it much easier f
users to diagnose and fix this common configuration issue.###

No source file, test, or entry point is named in the issue; start by locating the generic "Could not open '[sourcePath]' in the editor." error in the VS Code extension. Update the resulting guidance to mention checking both pathMapping and the Default Entrypoint setting, then verify the incorrect-configuration reproduction no longer gives only the generic message.