[JES] Fix a bug in handling follow operations. The 'what' was indeed a list,...

[JES] Fix a bug in handling follow operations. The 'what' was indeed a list, and the first element is expected to be a string but was a dict instead of a string, leading to the dreaded 'TypeError: unhashable type: dict' problem.

hive/indexer/follow.py

@@ -72,6 +72,8 @@ class Follow:
             return None
 
         what = first(op['what']) or ''
+        if not isinstance(what, str):
+            return None
         defs = {'': 0, 'blog': 1, 'ignore': 2}
         if what not in defs:
             return None