dragoncoder047
diff --git a/‎schemascii/__main__.py
Lines changed: 5 additions & 3 deletions b/‎schemascii/__main__.py
Lines changed: 5 additions & 3 deletions
diff --git a/‎schemascii/errors.py
Lines changed: 13 additions & 0 deletions b/‎schemascii/errors.py
Lines changed: 13 additions & 0 deletions
diff --git a/‎scripts/scriptutils.py
Lines changed: 1 addition & 4 deletions b/‎scripts/scriptutils.py
Lines changed: 1 addition & 4 deletions
@@ -1,4 +1,5 @@
 import argparse
+import os
 import sys
 import warnings
 
@@ -69,13 +70,15 @@ def cli_main():
             if args.out_file is None:
                 args.out_file = sys.stdout
         elif args.out_file is None:
-            args.out_file = open(args.in_file.name + ".svg")
+            args.out_file = open(args.in_file.name + ".svg", "w")
         try:
             with warnings.catch_warnings(record=True) as captured_warnings:
                 result_svg = schemascii.render(args.in_file.name,
                                                args.in_file.read(), args.fudge)
         except _errors.Error as err:
-            ap.error(str(err))
+            if args.out_file is not sys.stdout:
+                os.unlink(args.out_file.name)
+            ap.error(err.nice_message())
 
         if captured_warnings:
             for warning in captured_warnings:
@@ -86,7 +89,6 @@ def cli_main():
                 sys.exit(1)
 
         args.out_file.write(result_svg)
-
     finally:
         args.in_file.close()
         args.out_file.close()
 
@@ -1,26 +1,39 @@
 class Error(Exception):
     """A generic Schemascii error encountered when rendering a drawing."""
 
+    message_prefix: str | None = None
+
+    def nice_message(self) -> str:
+        return f"{self.message_prefix}{
+            ": " if self.message_prefix else ""
+        }{self!s}"
+
 
 class DiagramSyntaxError(SyntaxError, Error):
     """Bad formatting in Schemascii diagram syntax."""
+    message_prefix = "syntax error"
 
 
 class TerminalsError(ValueError, Error):
     """Incorrect usage of terminals on this component."""
+    message_prefix = "terminals error"
 
 
 class BOMError(ValueError, Error):
     """Problem with BOM data for a component."""
+    message_prefix = "BOM error"
 
 
 class UnsupportedComponentError(NameError, Error):
     """Component type is not supported."""
+    message_prefix = "unsupported component"
 
 
 class NoDataError(ValueError, Error):
     """Data item is required, but not present."""
+    message_prefix = "missing data item"
 
 
 class DataTypeError(TypeError, Error):
     """Invalid data type in data section."""
+    message_prefix = "invalid data type"
@@ -1,11 +1,8 @@
 import os
 import sys
-import typing
 
 # pylint: disable=missing-function-docstring
 
-T = typing.TypeVar("T")
-
 
 def cmd(sh_line: str, say: bool = True):
     if say:
@@ -25,6 +22,6 @@ def spit(file: os.PathLike, text: str):
         f.write(text)
 
 
-def spy(value: T) -> T:
+def spy[T](value: T) -> T:
     print(value)
     return value