Fix resume task. (backport #464)

CHANGELOG.md

@@ -17,6 +17,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 ### Deprecated
 ### Removed
 ### Fixed
+- Fix resume scan. [#464](https://github.com/greenbone/ospd/pull/464)
+
 
 [Unreleased]: https://github.com/greenbone/ospd/compare/v21.4.3...HEAD
 

ospd/scan.py

@@ -506,7 +506,17 @@ def get_end_time(self, scan_id: str) -> str:
     def get_host_list(self, scan_id: str) -> Dict:
         """Get a scan's host list."""
 
-        return self.scans_table[scan_id]['target'].get('hosts')
+        target = None
+        try:
+            target = self.scans_table[scan_id]['target'].get('hosts')
+        except KeyError:
+            logger.warning(
+                '%s: Scan ID is in the scan table, but it was '
+                'not initialized.',
+                scan_id,
+            )
+
+        return target
 
     def get_host_count(self, scan_id: str) -> int:
         """Get total host count in the target."""