query: Add a hint for the TypeError unhashable type: 'set'.

conservancy_beancount/reports/query.py

@@ -556,15 +556,12 @@ class BQLShell(bc_query_shell.BQLShell):
                 )
         except Exception as error:
             logger.error(str(error), exc_info=logger.isEnabledFor(logging.DEBUG))
-            if (isinstance(error, TypeError)
-                and error.args
-                and ' not supported between instances ' in error.args[0]):
-                logger.info(
-                    "HINT: Are you using ORDER BY or comparisons with metadata "
-                    "that isn't consistently set?\n  "
-                    "Try looking up that metadata with str_meta() instead to "
-                    "ensure your comparisons use a consistent data type.",
-                )
+            try:
+                hint_func = getattr(self, f'_hint_{type(error).__name__}')
+            except AttributeError:
+                pass
+            else:
+                hint_func(error, statement)
             return
 
         if not rows and output_format != 'ods':
@@ -573,6 +570,26 @@ class BQLShell(bc_query_shell.BQLShell):
             logger.debug("rendering query as %s", output_format)
             render_func(statement, row_types, rows)
 
+    def _hint_TypeError(self, error: TypeError, statement: QueryStatement) -> None:
+        try:
+            errmsg = str(error.args[0])
+        except IndexError:
+            return
+        if ' not supported between instances ' in errmsg:
+            logger.info(
+                "HINT: Are you using ORDER BY or comparisons with metadata "
+                "that isn't consistently set?\n  "
+                "Try looking up that metadata with str_meta() instead to "
+                "ensure your comparisons use a consistent data type.",
+            )
+        elif errmsg.startswith('unhashable type: '):
+            logger.info(
+                "HINT: bean-query does not support selecting columns or "
+                "functions that return multiple items as non-aggregate data in "
+                "GROUP BY queries.\n  "
+                "If you want to aggregate that data, run it through set().",
+            )
+
     def _render_csv(self, statement: QueryStatement, row_types: RowTypes, rows: Rows) -> None:
         bc_query_render.render_csv(
             row_types,

setup.py

@@ -5,7 +5,7 @@ from setuptools import setup
 setup(
     name='conservancy_beancount',
     description="Plugin, library, and reports for reading Conservancy's books",
-    version='1.19.3',
+    version='1.19.4',
     author='Software Freedom Conservancy',
     author_email='info@sfconservancy.org',
     license='GNU AGPLv3+',