Safely convert payloads to strings

For non-error tuples `Exception.normalize/3` returns the original
payload, which may be anything. Some payloads such as tuples don't
implement the `String.Chars` protocol. So cally `to_string/1` will fail.
In such cases we fall back to `inspect/1`.

Author: crbelaus

lib/error_tracker.ex

@@ -232,8 +232,19 @@ defmodule ErrorTracker do
       %struct{} = ex ->
         {to_string(struct), Exception.message(ex)}
 
-      other ->
-        {to_string(kind), to_string(other)}
+      payload ->
+        # For non-error tuples `Exception.normalize/3` returns the original payload, which may be
+        # anything. Some payloads such as tuples don't implement the `String.Chars` protocol. So
+        # calling `to_string/1` will fail. In such cases we fall back to `inspect/1`.
+        payload_as_string =
+          try do
+            to_string(payload)
+          rescue
+            Protocol.UndefinedError ->
+              inspect(payload)
+          end
+
+        {to_string(kind), payload_as_string}
     end
   end