fix: some adjuts to avoid `NOTICE` and `WARNING`

src/classes/api/endpoints/class-tainacan-rest-background-processes-controller.php

@@ -253,6 +253,7 @@ class REST_Background_Processes_Controller extends REST_Controller {
         $item->log = $this->get_log_url($key_log, $item->action);
         $item->error_log = $this->get_log_url($key_log, $item->action, 'error');
         $nonce = wp_create_nonce( 'wp_rest' );
+        $item->output = $item->output ?? '';
         $item->output = str_replace("&_wpnonce=[nonce]", "&_wpnonce=$nonce", $item->output);
         return $item;
     }
@@ -376,14 +377,14 @@ class REST_Background_Processes_Controller extends REST_Controller {
         $upload_url = wp_upload_dir();
         $path = $upload_url['basedir'] . '/tainacan/' . $guid;
         if ( file_exists( $path ) ) {
-            $finfo = finfo_open(FILEINFO_MIME_TYPE);
+            $finfo = @finfo_open(FILEINFO_MIME_TYPE);
-            $mime_type = finfo_file($finfo, $path);
+            $mime_type = @finfo_file($finfo, $path);
-            $file_name = basename($path);
+            $file_name = @basename($path);
             http_response_code(200);
             header('Content-Description: File Transfer');
             header("Content-Disposition: attachment; filename=$file_name"); 
             header("Content-Type: $mime_type");
-            header("Content-Length: " . filesize( $path ));
+            header("Content-Length: " . @filesize( $path ));
             \readfile($path);
         } else {
             return new \WP_REST_Response("file not found", 404, array('content-type' => 'text/html; charset=utf-8'));

src/classes/class-tainacan-background-process.php

@@ -347,7 +347,7 @@ abstract class Background_Process extends \Tainacan_WP_Background_Process {
 
 			$this->debug('Shutdown with Fatal error captured');
 			$this->debug($error_str);
-			$this->write_error_log($batch->key, [['datetime' => date("Y-m-d H:i:s"), 'message' => 'Fatal Error: ' . $error_str]] );
+			$this->write_error_log($batch->key, [['datetime' => date("Y-m-d H:i:s"), 'message' => 'Fatal Error: see the server error log for more details']] );
 			$this->write_error_log($batch->key, [['datetime' => date("Y-m-d H:i:s"), 'message' => 'Process aborted']]);
 			$this->close( $batch->key, 'errored' );
 			$this->debug('Batch closed due to captured error');
@@ -363,7 +363,7 @@ abstract class Background_Process extends \Tainacan_WP_Background_Process {
 			} catch (\Exception $e) {
 				// TODO: Add Stacktrace
 				$this->debug('Fatal Error: ' . $e->getMessage());
-				$this->write_error_log($batch->key, [['datetime' => date("Y-m-d H:i:s"), 'message' => 'Try Fatal Error: ' . $e->getMessage()]]);
+				$this->write_error_log($batch->key, [['datetime' => date("Y-m-d H:i:s"), 'message' => 'Try Fatal Error: see the server error log for more details']]);
 				$this->write_error_log($batch->key, [['datetime' => date("Y-m-d H:i:s"), 'message' => 'Process aborted']]);
 				$task = false;
 				$close_status = 'errored';

src/classes/exporter/class-tainacan-exporter.php

@@ -721,6 +721,10 @@ abstract class Exporter {
 	public function	append_to_file($key, $data) {
 		if ( array_key_exists ( $key , $this->output_files ) ) {
 			$fp = fopen($this->output_files[$key]['filename'], 'a');
+			if($fp == false) {
+				$file_name = $this->output_files[$key]['filename'];
+				throw new \Exception("Cannot open file $file_name");
+			}
 			fwrite($fp, $data);
 			fclose($fp);
 		} else { // será?

src/classes/repositories/class-tainacan-item-metadata.php

@@ -372,6 +372,10 @@ class Item_Metadata extends Repository {
 
 			$terms = wp_get_object_terms( $item_metadata->get_item()->get_id(), $taxonomy_slug );
 
+			if( is_wp_error($terms) ) {
+				return null;
+			}
+			
 			if ( $unique ) {
 				$terms = reset( $terms );