Fixed sketch profile parser crashing in some cases.

internal/arduino/sketch/profiles.go

@@ -124,6 +124,9 @@ type Profile struct {
 
 // UsesSystemPlatform checks if this profile requires a system installed platform.
 func (p *Profile) RequireSystemInstalledPlatform() bool {
+	if len(p.Platforms) == 0 {
+		return true
+	}
 	return p.Platforms[0].RequireSystemInstalledPlatform()
 }
 

internal/integrationtest/profiles/profiles_test.go

@@ -392,3 +392,21 @@ func TestProfileSetDefault(t *testing.T) {
 	require.Error(t, err)
 	require.Equal(t, "Cannot set inexistent_profile as default profile: Profile 'inexistent_profile' not found\n", string(stderr))
 }
+
+func TestProfileLoadingIssue3081(t *testing.T) {
+	// https://github.com/arduino/arduino-cli/issues/3081
+	env, cli := integrationtest.CreateArduinoCLIWithEnvironment(t)
+	defer env.CleanUp()
+
+	// Init the environment explicitly
+	_, _, err := cli.Run("core", "update-index")
+	require.NoError(t, err)
+	_, _, err = cli.Run("core", "install", "arduino:avr")
+	require.NoError(t, err)
+
+	// Compile problematic sketch
+	sk, err := paths.New("testdata", "Issue3081").Abs()
+	require.NoError(t, err)
+	_, _, err = cli.Run("compile", sk.String())
+	require.NoError(t, err)
+}

internal/integrationtest/profiles/testdata/Issue3081/Issue3081.ino

@@ -0,0 +1,2 @@
+void setup() {}
+void loop() {}

internal/integrationtest/profiles/testdata/Issue3081/sketch.yaml

@@ -0,0 +1,4 @@
+profiles:
+  garage:
+    fqbn: arduino:avr:uno
+default_profile: garage