fix(core): show descriptive error messages when saving settings fails (#18095)

Co-authored-by: Dev Randalpura <devrandalpura@google.com>

packages/cli/src/config/settings.test.ts

@@ -2594,7 +2594,7 @@ describe('Settings Loading and Merging', () => {
 
       expect(mockCoreEvents.emitFeedback).toHaveBeenCalledWith(
         'error',
-        'There was an error saving your latest settings changes.',
+        'Failed to save settings: Write failed',
         error,
       );
     });

packages/cli/src/config/settings.ts

@@ -14,6 +14,7 @@ import {
   FatalConfigError,
   GEMINI_DIR,
   getErrorMessage,
+  getFsErrorMessage,
   Storage,
   coreEvents,
   homedir,
@@ -1072,9 +1073,10 @@ export function saveSettings(settingsFile: SettingsFile): void {
       settingsToSave as Record<string, unknown>,
     );
   } catch (error) {
+    const detailedErrorMessage = getFsErrorMessage(error);
     coreEvents.emitFeedback(
       'error',
-      'There was an error saving your latest settings changes.',
+      `Failed to save settings: ${detailedErrorMessage}`,
       error,
     );
   }
@@ -1087,9 +1089,10 @@ export function saveModelChange(
   try {
     loadedSettings.setValue(SettingScope.User, 'model.name', model);
   } catch (error) {
+    const detailedErrorMessage = getFsErrorMessage(error);
     coreEvents.emitFeedback(
       'error',
-      'There was an error saving your preferred model.',
+      `Failed to save preferred model: ${detailedErrorMessage}`,
       error,
     );
   }