Clarify error message when plugin config parsers raise an error (#8492)

This turns:

    Failed to parse config for 'myplugin': Exception('error message')

into:

    Failed to parse config for 'myplugin': error message.

2 files changed, 2 insertions, 1 deletions

diff --git a/changelog.d/8492.misc b/changelog.d/8492.misc
new file mode 100644

index 0000000000..a344aee791
--- /dev/null
+++ b/changelog.d/8492.misc
@@ -0,0 +1 @@
+Clarify error message when plugin config parsers raise an error.
diff --git a/synapse/util/module_loader.py b/synapse/util/module_loader.py

index bb62db4637..94b59afb38 100644
--- a/synapse/util/module_loader.py
+++ b/synapse/util/module_loader.py
@@ -36,7 +36,7 @@ def load_module(provider):
     try:
         provider_config = provider_class.parse_config(provider.get("config"))
     except Exception as e:
-        raise ConfigError("Failed to parse config for %r: %r" % (provider["module"], e))
+        raise ConfigError("Failed to parse config for %r: %s" % (provider["module"], e))
 
     return provider_class, provider_config