Improve response messages if UF2 download fails during install command

circfirm/cli.py

@@ -88,10 +88,15 @@ def install(version: str, language: str, board: Optional[str]) -> None:
     uf2file = circfirm.backend.get_uf2_filepath(board, version, language)
     uf2filename = os.path.basename(uf2file)
     uf2_path = os.path.join(bootloader, uf2filename)
-    announce_and_await(
-        f"Copying UF2 to {board}", shutil.copyfile, args=(uf2file, uf2_path)
-    )
-    click.echo("Device should reboot momentarily.")
+    try:
+        announce_and_await(
+            f"Copying UF2 to {board}", shutil.copyfile, args=(uf2file, uf2_path)
+        )
+        click.echo("Device should reboot momentarily.")
+    except ConnectionError as err:
+        click.echo(" failed")  # Mark as failed
+        click.echo(f"Error: {err.args[0]}")
+        sys.exit(4)
 
 
 @cli.group()

tests/test_cli.py

@@ -48,6 +48,7 @@ def wait_and_add() -> None:
     ERR_NOT_FOUND = 1
     ERR_FOUND_CIRCUITPY = 2
     ERR_IN_BOOTLOADER = 3
+    ERR_UF2_DOWNLOAD = 4
     try:
         # Test not finding the mounted drive
         tests.helpers.delete_mount_node(circfirm.UF2INFO_FILE)
@@ -62,6 +63,13 @@ def wait_and_add() -> None:
             cli, ["install", version, "--board", "feather_m4_express"]
         )
         assert result.exit_code == ERR_FOUND_CIRCUITPY
+
+        # Test using bad board version
+        tests.helpers.copy_boot_out()
+        result = runner.invoke(
+            cli, ["install", "doesnotexist", "--board", "feather_m4_express"]
+        )
+        assert result.exit_code == ERR_UF2_DOWNLOAD
         tests.helpers.delete_mount_node(circfirm.BOOTOUT_FILE)
     finally:
         tests.helpers.copy_uf2_info()