IllegalStateException when loading contact

Three users reported this crash.

• Android version: 7.0, 7.0, 6.0.1
• Phone model: Huawei VNS-L31, Motorola Moto G (5) Plus, Xiaomi Redmi 3S (land)
• Briar version: 1.1.5 (8f4c3c45)

Stacktrace:

java.lang.IllegalStateException
        at org.briarproject.bramble.db.H2Database.createConnection(H2Database.java:99)
        at org.briarproject.bramble.db.JdbcDatabase.startTransaction(JdbcDatabase.java:540)
        at org.briarproject.bramble.db.JdbcDatabase.startTransaction(JdbcDatabase.java:83)
        at org.briarproject.bramble.db.DatabaseComponentImpl.startTransaction(DatabaseComponentImpl.java:143)
        at org.briarproject.bramble.db.DatabaseComponentImpl.transactionWithResult(DatabaseComponentImpl.java:187)
        at org.briarproject.bramble.contact.ContactManagerImpl.getContact(ContactManagerImpl.java:89)
        at org.briarproject.briar.android.conversation.ConversationViewModel.lambda$loadContact$1(ConversationViewModel.java:76)
        at org.briarproject.briar.android.conversation.-$$Lambda$ConversationViewModel$84zBaMmuwR5dlD6GPJnSkh4Cf4w.run(lambda)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607)
        at java.lang.Thread.run(Thread.java:776)