Check if raw P1/11 has records.

Even if it hasn't, the file gets imported anyway
(into the `files` table) but we exit early to avoid
an error when trying to determine shooting direction.

This check is not necessary for final P1/11 or gun data.

Fixes #104.

bin/datastore.py

@@ -392,6 +392,14 @@ class Datastore:
 			cursor.execute("BEGIN;")
 			
 			hash = self.add_file(filepath, cursor)
+			
+			if not records or len(records) == 0:
+				print("File has no records (or none have been detected)")
+				# We add the file to the database anyway to signal that we have
+				# actually seen it.
+				self.maybe_commit()
+				return
+
 			incr = p111.point_number(records[0]) <= p111.point_number(records[-1])
 
 			# Start by deleting any online data we may have for this sequence