send_json: print understandable json errors

at least: this works in the current set of circumstances

ingest/management/commands/send_json.py

@@ -16,6 +16,24 @@ from bugsink.streams import compress_with_zlib, WBITS_PARAM_FOR_GZIP, WBITS_PARA
 from projects.models import Project
 
 
+def understandable_json_error(e):
+    # When a JSON schema contains many anyOfs, the default error message does not contain any useful information
+    # (despite containing a lot of information). This function recursively traverses the "context" to extract, what I
+    # found in Sept 2024, to be the most useful information.
+
+    if e.context == []:
+        if e.message.endswith("is not of type 'null'"):
+            # when you implement 'nullable' as an anyOf with null, this will be half of the error messages, but not the
+            # useful half. So we just ignore it.
+            return ""
+
+        # no more children, we're at the node, let's return the actually-interesting information
+        return ("%s: " % e.json_path) + e.message
+
+    # we have children, let's recurse
+    return "\n".join([s for s in [understandable_json_error(suberror) for suberror in e.context] if s != ""])
+
+
 class Command(BaseCommand):
     help = "Send raw events to a sentry-compatible server; events can be sources from the filesystem or your DB."
 
@@ -44,7 +62,7 @@ class Command(BaseCommand):
 
             jsonschema.validate(data, schema)
         except jsonschema.ValidationError as e:
-            self.stderr.write("%s %s" % (repr(e), identifier))
+            self.stderr.write("%s %s" % (understandable_json_error(e), identifier))
             return False
 
         return True