Fix 'pickString' evaluation (#12100)

Similar to 'promptString', 'pickString' can be used to replace variables in task and
launch configurations. However 'pickString' values were not correctly handled which
prevented them from being evaluated. This is now fixed.

Fixes #11585

Contributed on behalf of STMicroelectronics

CHANGELOG.md

@@ -8,6 +8,7 @@
 
 - [plugin] added support for `isTransient` of `TerminalOptions` and `ExternalTerminalOptions` VS Code API [#12055](https://github.com/eclipse-theia/theia/pull/12055) - Contributed on behalf of STMicroelectronics
 - [terminal] added support for preference `terminal.integrated.enablePersistentSessions` to allow disabling restoring terminals on reload [#12055](https://github.com/eclipse-theia/theia/pull/12055) - Contributed on behalf of STMicroelectronics
+- [variable-resolver] fixed evaluations of `pickString` variables [#12100](https://github.com/eclipse-theia/theia/pull/12100) - Contributed on behalf of STMicroelectronics
 
 <a name="breaking_changes_1.34.0">[Breaking Changes:](#breaking_changes_1.34.0)</a>
 

packages/variable-resolver/src/browser/common-variable-contribution.ts

@@ -135,7 +135,8 @@ export class CommonVariableContribution implements VariableContribution {
                             });
                         }
                     }
-                    return this.quickInputService?.showQuickPick(elements, { placeholder: input.description });
+                    const selectedPick = await this.quickInputService?.showQuickPick(elements, { placeholder: input.description });
+                    return selectedPick?.value;
                 }
                 if (input.type === 'command') {
                     if (typeof input.command !== 'string') {