Raise JobMappingException when tool has been removed

That fixes the underlying problem in
https://github.com/galaxyproject/galaxy/issues/8141
but doesn't implement the outer try/except suggested
by @natefoo.

lib/galaxy/jobs/__init__.py

@@ -1173,6 +1173,9 @@ class JobWrapper(HasResourceParameters):
                       "destination for completion of fail method", self.get_id_tag(), str(exc.failure_message))
             self.job_runner_mapper.cached_job_destination = JobDestination(id='__fail__')
 
+        # Might be AssertionError or other exception
+        message = str(message)
+
         # if the job was deleted, don't fail it
         if not job.state == job.states.DELETED:
             # Check if the failure is due to an exception

lib/galaxy/jobs/mapper.py

@@ -207,6 +207,10 @@ class JobRunnerMapper(object):
         return job_destination
 
     def __determine_job_destination(self, params, raw_job_destination=None):
+        if self.job_wrapper.tool is None:
+            raise JobMappingException(
+                "Can't map job to destination, tool '%s' is unavailable" % self.job_wrapper.get_job().tool_id
+            )
         if raw_job_destination is None:
             raw_job_destination = self.job_wrapper.tool.get_job_destination(params)
         if raw_job_destination.runner == DYNAMIC_RUNNER_NAME:

test/integration/test_fail_job_tool_unavailable.py

@@ -1,4 +1,5 @@
 import time
+
 from base import integration_util
 from base.populators import (
     DatasetPopulator,