diff --git a/src/rp/cli.py b/src/rp/cli.py
index 440c2a0..318dfe1 100644
--- a/src/rp/cli.py
+++ b/src/rp/cli.py
@@ -50,7 +50,7 @@ def main(
         Optional[Path],
         typer.Argument(help="File to rich-print. Use '-' or omit to read from stdin."),
     ] = None,
-    type: Annotated[
+    file_type: Annotated[
         Optional[str],
         typer.Option(
             "--type", "-t", help="Force file type (e.g. json, python, markdown)."
@@ -89,6 +89,8 @@ def main(
     console = Console()
 
     if file is None or str(file) == "-":
+        if sys.stdin.isatty():
+            console.print("[dim]Reading from stdin. Press Ctrl+D to end.[/dim]")
         content = sys.stdin.read()
         file_path = None
     else:
@@ -98,14 +100,21 @@ def main(
         if file.is_dir():
             console.print(f"[red]Error:[/red] Is a directory: {file}")
             raise typer.Exit(code=1)
-        content = file.read_text(encoding="utf-8")
+        try:
+            content = file.read_text(encoding="utf-8")
+        except UnicodeDecodeError:
+            console.print(f"[red]Error:[/red] Cannot read binary file: {file}")
+            raise typer.Exit(code=1)
+        except (PermissionError, OSError) as e:
+            console.print(f"[red]Error:[/red] {e}")
+            raise typer.Exit(code=1)
         file_path = str(file)
 
     if not content:
         console.print("[dim]Empty input, nothing to display.[/dim]")
         raise typer.Exit()
 
-    file_type = detect_type(path=file_path, content=content, explicit_type=type)
+    file_type = detect_type(path=file_path, content=content, explicit_type=file_type)
 
     options = RenderOptions(
         theme=theme,
diff --git a/src/rp/detect.py b/src/rp/detect.py
index d199b5d..19c2f50 100644
--- a/src/rp/detect.py
+++ b/src/rp/detect.py
@@ -40,7 +40,6 @@ EXTENSION_MAP: dict[str, str] = {
     ".swift": "swift",
     ".kt": "kotlin",
     ".r": "r",
-    ".R": "r",
     ".lua": "lua",
     ".dockerfile": "docker",
     ".ini": "ini",
diff --git a/src/rp/render.py b/src/rp/render.py
index 158e925..d4ae8f3 100644
--- a/src/rp/render.py
+++ b/src/rp/render.py
@@ -39,7 +39,7 @@ def render(
     elif file_type in _JSON_TYPES:
         try:
             renderable = RichJSON(content)
-        except Exception:
+        except (SyntaxError, ValueError):
             renderable = Syntax(
                 content, "json", theme=options.theme, line_numbers=line_numbers
             )