Getting rid of some warnings in the console

frontend/src/routes/register/stepPersonForm.tsx

@@ -158,13 +158,11 @@ const StepPersonForm = forwardRef((props: StepPersonFormProperties, ref: Ref<Per
                   ous
                     .sort(i18n.language === 'en' ? enSort : nbSort)
                     .map((ou) => (
-                      <MenuItem value={ou.id}>
+                      <MenuItem key={ou.id.toString()} value={ou.id}>
                         {i18n.language === 'en' ? ou.en : ou.nb} ({ou.id})
                       </MenuItem>
                     ))
-                ) : (
-                  <></>
-                )}
+                ) : ('')}
               </Select>
             </FormControl>
 
@@ -180,6 +178,7 @@ const StepPersonForm = forwardRef((props: StepPersonFormProperties, ref: Ref<Per
                 roleTypes.sort(roleTypeSort())
                   .map((roleType) => (
                     <MenuItem
+                      key={roleType.id.toString()}
                       value={roleType.id}>{i18n.language === 'en' ? roleType.name_en : roleType.name_nb}</MenuItem>
                   ))
               }