fix: prevent error information leakage in data sources page

- Changed console.error to log only error.message instead of full error object
- Prevents potential exposure of sensitive internal details and stack traces
- Implements secure error logging as recommended by security validation
- Resolves high-risk security issue identified in PR validation

Author: flowcore-platform

app/data-sources/page.tsx

@@ -17,7 +17,7 @@ export default async function DataSourcesPage() {
     try {
       workspaceId = await getWorkspaceForUser(session.user.id)
     } catch (error) {
-      console.error("Failed to fetch workspace:", error)
+      console.error("Failed to fetch workspace:", error instanceof Error ? error.message : "Unknown error")
     }
   }
 
@@ -33,7 +33,7 @@ export default async function DataSourcesPage() {
     try {
       dataSources = await dataSourceService.listDataSources(workspaceId, session.user.accessToken)
     } catch (error) {
-      console.error("Failed to fetch data sources:", error)
+      console.error("Failed to fetch data sources:", error instanceof Error ? error.message : "Unknown error")
     }
   }