Gracefully handle absence of tasks in management extension

When task doesn't exist while it was requested the codebase fails with NPE which results in 500 response. Rework it to gracefully handle such cases and let client know that task is missing.

The example of code that fails

tw-tasks-executor/tw-tasks-management/src/main/java/com/transferwise/tasks/management/TasksManagementPortController.java

Lines 102 to 118 in 15ec5dc

    
           @Override 
        
           public ResponseEntity<TaskWithoutData> getTask(@PathVariable final String taskId) { 
        
             return callWithAuthentication(() -> { 
        
               FullTaskRecord task = taskDao.getTask(UUID.fromString(taskId), FullTaskRecord.class); 
        
               return ResponseEntity.ok(new TaskWithoutData() 
        
                   .setId(taskId) 
        
                   .setVersion(task.getVersion()) 
        
                   .setStatus(task.getStatus()) 
        
                   .setType(task.getType()) 
        
                   .setSubType(task.getSubType()) 
        
                   .setNextEventTime(Date.from(task.getNextEventTime().toInstant())) 
        
                   .setStateTime(Date.from(task.getStateTime().toInstant())) 
        
                   .setPriority(task.getPriority()) 
        
                   .setProcessingTriesCount(task.getProcessingTriesCount()) 
        
                   .setProcessingClientId(task.getProcessingClientId())); 
        
             }); 
        
           }

Stale issue message

	@Override
	public ResponseEntity<TaskWithoutData> getTask(@PathVariable final String taskId) {
	return callWithAuthentication(() -> {
	FullTaskRecord task = taskDao.getTask(UUID.fromString(taskId), FullTaskRecord.class);
	return ResponseEntity.ok(new TaskWithoutData()
	.setId(taskId)
	.setVersion(task.getVersion())
	.setStatus(task.getStatus())
	.setType(task.getType())
	.setSubType(task.getSubType())
	.setNextEventTime(Date.from(task.getNextEventTime().toInstant()))
	.setStateTime(Date.from(task.getStateTime().toInstant()))
	.setPriority(task.getPriority())
	.setProcessingTriesCount(task.getProcessingTriesCount())
	.setProcessingClientId(task.getProcessingClientId()));
	});
	}