Miscellaneous small fixes...

* Syntax Errors showing more properly by removing weird SymbolForm
  handling. Also get ready for an "error" kind of format
* Remove GNU Readline termshell style error when no style given
* Better error checking on giving a file argument for an invalid file

Author: rocky

mathicsscript/__main__.py

@@ -469,29 +469,40 @@ def main(
 
     load_settings_file(shell)
     style_from_settings_file = definitions.get_ownvalue("Settings`$PygmentsStyle")
-    if style_from_settings_file is SymbolNull and style is None:
+    if style_from_settings_file is not SymbolNull and style is None:
         style = style_from_settings_file
     shell.setup_pygments_style(style)
 
     if file:
-        with open(file, "r") as ifile:
-            feeder = MathicsFileLineFeeder(ifile)
+        if not os.path.exists(file):
+            print(f"\nFile {file} does not exist; skipping reading.")
+            file = None
+        elif os.path.isdir(file):
+            print(f"\nFile {file} does is a directory; skipping reading.")
+            file = None
+        else:
             try:
-                while not feeder.empty():
-                    evaluation = Evaluation(
-                        shell.definitions,
-                        output=TerminalOutput(shell),
-                        catch_interrupt=False,
-                        format="text",
-                    )
-                    query = evaluation.parse_feeder(feeder)
-                    if query is None:
-                        continue
-                    evaluation.evaluate(query, timeout=settings.TIMEOUT)
-            except KeyboardInterrupt:
-                print("\nKeyboardInterrupt")
-
-        definitions.set_line_no(0)
+                with open(file, "r") as ifile:
+                    feeder = MathicsFileLineFeeder(ifile)
+                    try:
+                        while not feeder.empty():
+                            evaluation = Evaluation(
+                                shell.definitions,
+                                output=TerminalOutput(shell),
+                                catch_interrupt=False,
+                                format="text",
+                            )
+                            query = evaluation.parse_feeder(feeder)
+                            if query is None:
+                                continue
+                            evaluation.evaluate(query, timeout=settings.TIMEOUT)
+                    except KeyboardInterrupt:
+                        print("\nKeyboardInterrupt")
+            except Exception as e:
+                print(f"\nError reading {file}: {e}; skipping reading.")
+                file = None
+            else:
+                definitions.set_line_no(0)
 
     if code:
         for expr in code:

mathicsscript/format.py

@@ -168,15 +168,18 @@ def eval_boxes(result, fn: Callable, obj, **options):
         obj.last_eval = SymbolAborted
         return "$Aborted"
     if format == "text":
-        if expr_head is SymbolStringForm:
-            return expr.elements[0].value
-        elif isinstance(expr, String):
+        if isinstance(expr, String):
             return expr.value
         result = expr.format(obj, SymbolOutputForm)
     elif format == "xml":
         result = Expression(SymbolStandardForm, expr).format(obj, SymbolMathMLForm)
     elif format == "tex":
         result = Expression(SymbolStandardForm, expr).format(obj, SymbolTeXForm)
+    elif format == "error":
+        # We may do fancier things in the future.
+        if isinstance(expr, String):
+            return expr.value
+        result = expr.format(obj, SymbolOutputForm)
     elif format == "unformatted":
         if expr_head is PyMathicsGraph and hasattr(expr, "G"):
             return format_graph(expr.G)

mathicsscript/termshell.py

@@ -10,7 +10,7 @@
 import mathics_scanner.location
 
 from columnize import columnize
-from mathics.core.atoms import Symbol
+from mathics.core.atoms import String, Symbol
 from mathics.core.attributes import attribute_string_to_number
 from mathics.core.expression import Expression, from_python  # strip_context,
 from mathics.core.rules import Rule
@@ -238,7 +238,8 @@ def print_result(
             out_str = str(result.result)
             use_highlight = True
             if eval_type == "System`String":
-                if strict_wl_output:  # exact-wl-compatibility
+                # Use exact-wl-compatibility?
+                if strict_wl_output:
                     out_str = (
                         format(
                             [(MToken.STRING, out_str.rstrip())], self.terminal_formatter
@@ -263,6 +264,7 @@ def print_result(
 
             if eval_type == "System`Graph":
                 out_str = "-Graph-"
+
             elif self.terminal_formatter:  # pygmentize
                 show_pygments_tokens = get_settings_value(
                     self.definitions, "Settings`$PygmentsShowTokens"

mathicsscript/termshell_prompt.py

@@ -164,7 +164,8 @@ def print_result(
             out_str = str(result.result)
             use_highlight = True
             if eval_type == "System`String":
-                if strict_wl_output:  # exact-wl-compatibility
+                # Use exact-wl-compatibility?
+                if strict_wl_output:
                     out_str = (
                         format(
                             [(MToken.STRING, out_str.rstrip())], self.terminal_formatter
@@ -189,8 +190,8 @@ def print_result(
 
             if eval_type == "System`Graph":
                 out_str = "-Graph-"
-            elif self.terminal_formatter:  # pygmentize
 
+            elif self.terminal_formatter:  # pygmentize
                 if show_pygments_tokens:
                     print(list(lex(out_str, mma_lexer)))
                 if use_highlight: