Allow optional programmer in debug (#2544)

This is a cherry-pick of https://github.com/arduino/arduino-cli/pull/2540
from the 0.35.x branch

commands/debug/debug_info.go

@@ -154,15 +154,14 @@ func getDebugProperties(req *rpc.GetDebugConfigRequest, pme *packagemanager.Expl
 		}
 	}
 
-	if req.GetProgrammer() == "" {
-		return nil, &cmderrors.MissingProgrammerError{}
-	}
-	if p, ok := platformRelease.Programmers[req.GetProgrammer()]; ok {
-		toolProperties.Merge(p.Properties)
-	} else if refP, ok := referencedPlatformRelease.Programmers[req.GetProgrammer()]; ok {
-		toolProperties.Merge(refP.Properties)
-	} else {
-		return nil, &cmderrors.ProgrammerNotFoundError{Programmer: req.GetProgrammer()}
+	if req.GetProgrammer() != "" {
+		if p, ok := platformRelease.Programmers[req.GetProgrammer()]; ok {
+			toolProperties.Merge(p.Properties)
+		} else if refP, ok := referencedPlatformRelease.Programmers[req.GetProgrammer()]; ok {
+			toolProperties.Merge(refP.Properties)
+		} else {
+			return nil, &cmderrors.ProgrammerNotFoundError{Programmer: req.GetProgrammer()}
+		}
 	}
 
 	var importPath *paths.Path

commands/debug/debug_test.go

@@ -65,12 +65,6 @@ func TestGetCommandLine(t *testing.T) {
 	pme, release := pm.NewExplorer()
 	defer release()
 
-	{
-		// Check programmer required
-		_, err := getCommandLine(req, pme)
-		require.Error(t, err)
-	}
-
 	{
 		// Check programmer not found
 		req.Programmer = "not-existent"

internal/integrationtest/debug/debug_test.go

@@ -336,9 +336,6 @@ func testAllDebugInformation(t *testing.T, env *integrationtest.Environment, cli
 }
 
 func testDebugCheck(t *testing.T, env *integrationtest.Environment, cli *integrationtest.ArduinoCLI) {
-	_, _, err := cli.Run("debug", "check", "-b", "arduino:samd:mkr1000")
-	require.Error(t, err)
-
 	out, _, err := cli.Run("debug", "check", "-b", "arduino:samd:mkr1000", "-P", "atmel_ice")
 	require.NoError(t, err)
 	require.Contains(t, string(out), "The given board/programmer configuration supports debugging.")