api/deposit_status: Fix unexpected type error

Ids can be other types than string, join will not work on those.
This commit fixes it.

swh/deposit/api/deposit_status.py

@@ -52,7 +52,7 @@ def convert_status_detail(status_detail):
                 suffix_msg = ''
                 fields = data.get('fields')
                 if fields:
-                    suffix_msg = ' (%s)' % ', '.join(fields)
+                    suffix_msg = ' (%s)' % ', '.join(map(str, fields))
                 msg.append('- %s%s\n' % (data['summary'], suffix_msg))
 
     _detail = status_detail.get('url')
@@ -60,7 +60,7 @@ def convert_status_detail(status_detail):
         fields = _detail.get('fields')
         suffix_msg = ''
         if fields:
-            suffix_msg = ' (%s)' % ', '.join(fields)
+            suffix_msg = ' (%s)' % ', '.join(map(str, fields))
         msg.append('- %s%s\n' % (_detail['summary'], suffix_msg))
 
     if not msg:

swh/deposit/tests/api/test_deposit_status.py

@@ -218,6 +218,41 @@ class DepositStatusTestCase(APITestCase, WithAuthTestCase, BasicTestCase,
         actual_status_detail = convert_status_detail(status_detail)
         self.assertEqual(actual_status_detail, expected_status_detail)
 
+    @istest
+    def convert_status_detail_edge_case(self):
+        status_detail = {
+            'url': {
+                'summary': 'At least one compatible url field. Failed',
+                'fields': ['testurl'],
+            },
+            'metadata': [
+                {
+                    'summary': 'Mandatory fields missing',
+                    'fields': ['9', 10, 1.212],
+                },
+            ],
+            'archive': [
+                {
+                    'summary': 'Invalid archive',
+                    'fields': ['3'],
+                },
+                {
+                    'summary': 'Unsupported archive',
+                    'fields': [2],
+                }
+            ],
+        }
+
+        expected_status_detail = '''- Mandatory fields missing (9, 10, 1.212)
+- Invalid archive (3)
+- Unsupported archive (2)
+- At least one compatible url field. Failed (testurl)
+'''
+
+        actual_status_detail = convert_status_detail(status_detail)
+
+        self.assertEqual(actual_status_detail, expected_status_detail)
+
     @istest
     def status_on_deposit_rejected(self):
         _status = DEPOSIT_STATUS_REJECTED