fix[lang]: show user error in error map

vyper/codegen/ir_node.py

@@ -378,9 +378,7 @@ def is_complex_ir(self):
             and self.value.lower() not in do_not_cache
         )
 
-    # set an error message and push down into all children.
-    # useful for overriding an error message generated by a helper
-    # function with a more specific error message.
+    # set an error message and push down to its children.
     def set_error_msg(self, error_msg: str) -> None:
         if self.error_msg is not None:
             raise CompilerPanic(f"{self.value} already has error message {self.error_msg}")
@@ -600,7 +598,7 @@ def from_list(
     ) -> "IRnode":
         if isinstance(typ, str):  # pragma: nocover
             raise CompilerPanic(f"Expected type, not string: {typ}")
-
+        ret = None
         if isinstance(obj, IRnode):
             # note: this modify-and-returnclause is a little weird since
             # the input gets modified. CC 20191121.
@@ -612,12 +610,10 @@ def from_list(
                 obj.location = location
             if obj.encoding is None:
                 obj.encoding = encoding
-            if obj.error_msg is None:
-                obj.error_msg = error_msg
 
-            return obj
+            ret = obj
         elif not isinstance(obj, list):
-            return cls(
+            ret = cls(
                 obj,
                 [],
                 typ,
@@ -627,12 +623,11 @@ def from_list(
                 add_gas_estimate=add_gas_estimate,
                 ast_source=ast_source,
                 encoding=encoding,
-                error_msg=error_msg,
                 is_self_call=is_self_call,
                 passthrough_metadata=passthrough_metadata,
             )
         else:
-            return cls(
+            ret = cls(
                 obj[0],
                 [cls.from_list(o, ast_source=ast_source) for o in obj[1:]],
                 typ,
@@ -642,7 +637,9 @@ def from_list(
                 ast_source=ast_source,
                 add_gas_estimate=add_gas_estimate,
                 encoding=encoding,
-                error_msg=error_msg,
                 is_self_call=is_self_call,
                 passthrough_metadata=passthrough_metadata,
             )
+        if error_msg is not None:
+            ret.set_error_msg(error_msg)
+        return ret

vyper/codegen/stmt.py

@@ -156,9 +156,7 @@ def _assert_reason(self, test_expr, msg):
         else:
             ir_node = ["if", ["iszero", test_expr], revert_seq]
 
-        ir_node = IRnode.from_list(ir_node)
-        ir_node.set_error_msg("user revert with reason")
-        return ir_node
+        return IRnode.from_list(ir_node, error_msg="user revert with reason")
 
     def parse_Assert(self):
         test_expr = Expr.parse_value_expr(self.stmt.test, self.context)