Crash on Palo Alto with incomplete OSPF settings

[Dan Halperin]

Describe the bug and expected behavior
Batfish crashes when parsing incomplete interface OSPF settings

Runnable example

from pybatfish.client.session import Session
TXT = """
set deviceconfig system hostname EXAMPLE
set network interface ethernet ethernet1 layer3 units ethernet1.1 tag 1
set network virtual-router VR protocol ospf enable yes
set network virtual-router VR protocol ospf router-id 1.1.1.1
set network virtual-router VR protocol ospf area 0.0.0.0 interface ethernet1.1 link-type broadcast 
set network virtual-router VR interface ethernet1.1
"""
bf = Session()
bf.set_network("github-bug-report")
bf.init_snapshot_from_text(TXT)
# Verify that Batfish recognized the vendor format correctly
print(bf.q.fileParseStatus().answer())
# Insert command(s) below to demonstrate the problem
print(bf.q.initIssues().answer())

[Dan Halperin]

Reported by @racsoce