Ignore VariableDoesNotExist errors in debug logging

They're so noisy as to make debug logging useless otherwise

bookwyrm/settings.py

@@ -147,6 +147,9 @@ LOGGING = {
         "require_debug_true": {
             "()": "django.utils.log.RequireDebugTrue",
         },
+        "ignore_missing_variable": {
+            "()": "bookwyrm.utils.log.IgnoreVariableDoesNotExist",
+        },
     },
     "handlers": {
         # Overrides the default handler to make it log to console
@@ -154,6 +157,7 @@ LOGGING = {
         # console if DEBUG=False)
         "console": {
             "level": LOG_LEVEL,
+            "filters": ["ignore_missing_variable"],
             "class": "logging.StreamHandler",
         },
         # This is copied as-is from the default logger, and is

bookwyrm/utils/log.py

@@ -0,0 +1,12 @@
+import logging
+
+
+class IgnoreVariableDoesNotExist(logging.Filter):
+    def filter(self, record):
+        if(record.exc_info):
+            (errType, errValue, _) = record.exc_info
+            while errValue:
+                if type(errValue).__name__ == 'VariableDoesNotExist':
+                    return False
+                errValue = errValue.__context__
+            return True