Treat Windows Swift LLDB setup fail differently (#307)

* Fail silently if windows fails to find Swift LLDB

This is most likely due to Swift LLDB not running correctly
due to $PYTHONHOME being set incorrectly.

* add a return

* Improve comment message

Author: adam-fowler

src/WorkspaceContext.ts

@@ -284,9 +284,11 @@ export class WorkspaceContext implements vscode.Disposable {
     async setLLDBVersion() {
         const libPathResult = await getLLDBLibPath(this.toolchain);
         if (!libPathResult.success) {
-            const errorMessage = libPathResult.failure
-                ? `Error: ${getErrorDescription(libPathResult.failure)}`
-                : "";
+            // if failure message is undefined then fail silently
+            if (!libPathResult.failure) {
+                return;
+            }
+            const errorMessage = `Error: ${getErrorDescription(libPathResult.failure)}`;
             vscode.window.showErrorMessage(
                 `Failed to setup CodeLLDB for debugging of Swift code. Debugging may produce unexpected results. ${errorMessage}`
             );

src/debugger/lldb.ts

@@ -38,7 +38,14 @@ export async function getLLDBLibPath(toolchain: SwiftToolchain): Promise<Result<
             pathHint = m[1];
         }
     } catch (error) {
-        // ignore error
+        // If we get an error on Windows here we should not attempt to use the fallback path. If it failed
+        // it is most likely due to lldb failing to run because $PYHTONHOME environment variable is setup
+        // incorrectly (this is the case in Swift < 5.7). In this situation swift lldb does not work so we
+        // should just the version of lldb that comes with CodeLLDB. We return a failure with no message
+        // to indicate we want it to fail silently.
+        if (process.platform === "win32") {
+            return Result.makeFailure(undefined);
+        }
     }
     const lldbPath = await findLibLLDB(pathHint);
     if (lldbPath) {