Add user-friendly message when missing importer (#1959)

jrnl/commands.py

@@ -76,7 +76,17 @@ def postconfig_import(args: argparse.Namespace, config: dict, **_) -> int:
     journal = open_journal(args.journal_name, config)
 
     format = args.export if args.export else "jrnl"
-    get_importer(format).import_(journal, args.filename)
+
+    if (importer := get_importer(format)) is None:
+        raise JrnlException(
+            Message(
+                MsgText.ImporterNotFound,
+                MsgStyle.ERROR,
+                {"format": format},
+            )
+        )
+
+    importer.import_(journal, args.filename)
 
     return 0
 

jrnl/messages/MsgText.py

@@ -266,6 +266,11 @@ class MsgText(Enum):
         {count} imported to {journal_name} journal
         """
 
+    ImporterNotFound = """
+        No importer found for file type '{format}'.
+        '{format}' is likely to be an export-only format.
+        """
+
     # --- Color --- #
     InvalidColor = "{key} set to invalid color: {color}"