exceptions can have a detailed message that is only used for leaf errors

schema_salad/exceptions.py

@@ -15,9 +15,11 @@ def __init__(
         sl: Optional[SourceLine] = None,
         children: Optional[Sequence["SchemaSaladException"]] = None,
         bullet_for_children: str = "",
+        detailed_message: Optional[str] = None,
     ) -> None:
         super().__init__(msg)
         self.message = self.args[0]
+        self.detailed_message = detailed_message
         self.file: Optional[str] = None
         self.start: Optional[tuple[int, int]] = None
         self.end: Optional[tuple[int, int]] = None
@@ -97,14 +99,23 @@ def summary(self, level: int = 0, with_bullet: bool = False) -> str:
         indent_per_level = 2
         spaces = (level * indent_per_level) * " "
         bullet = self.bullet + " " if len(self.bullet) > 0 and with_bullet else ""
-        return f"{self.prefix()}{spaces}{bullet}{self.message}"
+        message_string = (
+            self.detailed_message
+            if (len(self.children) < 1 and self.detailed_message)
+            else self.message
+        )
+        return f"{self.prefix()}{spaces}{bullet}{message_string}"
 
     def __str__(self) -> str:
         """Convert to a string using :py:meth:`pretty_str`."""
         return str(self.pretty_str())
 
     def pretty_str(self, level: int = 0) -> str:
-        messages = len(self.message)
+        messages = (
+            len(self.message)
+            if len(self.children) > 0
+            else len(self.detailed_message or self.message)
+        )
         my_summary = [self.summary(level, True)] if messages else []
         next_level = level + 1 if messages else level