fix(cache): add log email cache errors (#1181)

## What?

Added error handling and logging to email body caching operations in
`main.go`. Previously, `config.SaveEmailBody()` calls were ignoring
errors with `_`, now they capture and log failures for both synchronous
and asynchronous caching scenarios.


## Why?

Email body caching could fail silently due to disk full or permission
denied errors, making debugging difficult when users experienced missing
cached emails. This change adds visibility into caching failures to help
diagnose storage-related issues.

closes: #1030

Author: joserafaelSH

main.go

@@ -733,12 +733,17 @@ func (m *mainModel) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 					Inline:    a.Inline,
 				})
 			}
-			go config.SaveEmailBody(folderName, config.CachedEmailBody{
-				UID:         msg.UID,
-				AccountID:   msg.AccountID,
-				Body:        msg.Body,
-				Attachments: cachedAttachments,
-			})
+			go func() {
+				err := config.SaveEmailBody(folderName, config.CachedEmailBody{
+					UID:         msg.UID,
+					AccountID:   msg.AccountID,
+					Body:        msg.Body,
+					Attachments: cachedAttachments,
+				})
+				if err != nil {
+					log.Printf("debug: error caching email body fails (disk full, permission denied) for UID: %d: %v", msg.UID, err)
+				}
+			}()
 		}
 		// Forward to FolderInbox for rendering
 		if m.folderInbox != nil {
@@ -1260,13 +1265,17 @@ func (m *mainModel) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
 			}
 			cachedAttachments = append(cachedAttachments, ca)
 		}
-		_ = config.SaveEmailBody(folderForCache, config.CachedEmailBody{
+		err := config.SaveEmailBody(folderForCache, config.CachedEmailBody{
 			UID:         msg.UID,
 			AccountID:   msg.AccountID,
 			Body:        msg.Body,
 			Attachments: cachedAttachments,
 		})
 
+		if err != nil {
+			log.Printf("debug: error caching email body fails (disk full, permission denied) for UID: %d: %v", msg.UID, err)
+		}
+
 		email := m.getEmailByUIDAndAccount(msg.UID, msg.AccountID, msg.Mailbox)
 		if email == nil {
 			if m.folderInbox != nil {